| HS Code | 226117 |
| Chemical Name | N-(tert-Butoxycarbonyl)glycine |
| Cas Number | 4530-20-5 |
| Molecular Formula | C7H13NO4 |
| Molecular Weight | 175.18 g/mol |
| Melting Point | 88-92 °C |
| Appearance | White crystalline powder |
| Solubility | Soluble in ethanol, methanol, DMF, DMSO; slightly soluble in water |
| Storage Conditions | Store at 2-8°C, sealed, and dry |
| Purity | ≥98% |
| Synonyms | N-Boc-glycine; tert-Butoxycarbonyl-glycine; Boc-Gly-OH |
As an accredited BOC-Glycine factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | BOC-Glycine is supplied as a white crystalline powder, 25 g per glass bottle, stored sealed at 2–8°C. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with BOC-Glycine, packed in sealed drums on pallets, secured and ready for shipment. |
| Shipping | BOC-Glycine ships as a white crystalline powder in sealed, moisture-resistant containers. Store at 2–8°C, away from heat, light, and humidity. Handle with standard laboratory PPE. Not classified as hazardous under normal transport conditions, but avoid dust inhalation and contact with eyes or skin. |
| Storage | Store BOC-Glycine in a tightly sealed container under refrigerated conditions (2–8°C). Keep it dry by using a desiccant, and protect from direct light and heat. Avoid repeated opening to prevent moisture absorption. Under these conditions, the compound remains stable for its recommended shelf life. Always follow the label and safety data sheet. |
| Shelf Life | Store at 2–8°C, desiccated and protected from moisture/heat. Shelf life is typically 2–3 years if unopened. |
BOC-Glycine (4530-20-5, molecular mass 175.18 g/mol) enters Boc/benzyl solid-phase peptide synthesis as the N-protected glycyl monomer on 4-methylbenzhydrylamine or phenylacetamidomethyl resins with substitution ranges of 0.4–1.0 mmol/g. In GMP peptide campaigns, the monomer is preactivated with N,N′-diisopropylcarbodiimide and 1-hydroxybenzotriazole in dimethylformamide/N-methyl-2-pyrrolidone. The addition ratio is typically 2.0–4.0 mol equiv relative to resin free amine, because Boc-Gly-OH coupling on MBHA resin under high substitution shows incomplete Kaiser-negative at 1.5 equiv after 60 min in some pilot batches. Coupling temperature is held at 20–25 °C; lower temperatures reduce DIC-mediated N-acylurea formation but extend reaction time to 120–180 min. Deprotection uses trifluoroacetic acid/dichloromethane 1:1 (v/v) with 0.5% (v/v) ethanedithiol; the BOC group is removed in 2 × 30 min washes. Final release from the resin requires anhydrous hydrogen fluoride with p-cresol as scavenger at −5 to 0 °C for 60–90 min in a Kel-F or Teflon-lined vessel equipped with a calcium oxide trap. The production terminal product consists of glycyl-containing peptide APIs or peptide fragments for subsequent purification by preparative reversed-phase HPLC; residual moisture after lyophilization is controlled to ≤5.0% (w/w) by Karl Fischer titration according to USP <921> Method Ic. Compliance references include ICH Q7 Section 12.10 for solvent recovery and 21 CFR 210.1/211.65 for equipment construction; where residual DMF is present, the limit follows ICH Q3C Class 2 solvent requirements.
Process conflicts in BOC SPPS with glycine arise at the deprotection boundary because the BOC group is acid-labile. Exposure to trace hydrogen chloride in dimethylformamide above 0.01 N at room temperature creates prematurely deblocked amine, leading to double coupling and truncated sequences. In addition, Boc-Gly-OH has no side-chain protecting group, so diketopiperazine formation can occur when the N-terminal glycine is deprotected and the following residue is proline or an N-methylamino acid. This is minimized by deprotection at 4 °C and immediate coupling within 15 min. Equipment in production includes a sintered-glass reactor with overhead mechanical agitation or nitrogen bubbling through a frit; batch-to-batch resin swelling in dichloromethane is confirmed at 3–5 mL/g before first coupling. Failure to control resin swelling below 4 mL/g may cause channeling in the packed bed and lower coupling yield by 8–15% in large-column runs. These are known field observations in pilot-scale SPPS reactors with internal diameter above 20 cm.
| Process parameter | Set point or range | Associated standard or equipment |
|---|---|---|
| MBHA/PAM resin substitution | 0.4–1.0 mmol/g | Sintered-glass SPPS vessel |
| Boc-Gly-OH/resin amine ratio | 2.0–4.0 mol equiv | ICH Q7 Section 12.10 |
| Coupling temperature/time | 20–25 °C for 45–120 min | Kaiser test endpoint |
| BOC deprotection | TFA/DCM 1:1 (v/v) with 0.5% EDT | USP <921> Method Ic for moisture |
| Final cleavage | HF/p-cresol 9:1 at −5 to 0 °C | Teflon-lined reactor, calcium oxide trap |
Solution-phase coupling with BOC-Glycine is applied in fragment condensation for short peptide intermediates where the target molecule is too small to justify resin-based synthesis. The activated species is most commonly Boc-Gly-OSu or Boc-Gly-ONp, generated from BOC-Glycine and N-hydroxysuccinimide using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride in tetrahydrofuran/dimethylformamide at 0–5 °C. The stoichiometric ratio in the subsequent aminolysis is 1.05–1.20 mol equiv of active ester per mol of amino component; if the amino component is a glycine-derived ester hydrochloride, 1.10–1.20 equiv of N-methylmorpholine is added concurrently to maintain a solution pH of 7.5–8.5. Water content in the reaction solvent is held at <0.1% (w/w) by Karl Fischer titration per ASTM E203; above 0.3%, active ester hydrolysis becomes measurable by LC-MS and reduces isolated yield by 5–12% in batch vessels with jacket temperature control at ±1 °C.
The process is carried out in a glass-lined steel reactor with a nitrogen purge and a brine-cooled jacket at −5 to +5 °C during activation, then warmed to 20–25 °C for aminolysis over 6–16 h. Residual dicyclohexylurea or diisopropylurea from the carbodiimide is removed by filtration through a 0.45 μm PTFE filter or by aqueous extraction with 5% (w/v) citric acid and 5% (w/v) sodium bicarbonate. The terminal product types are protected glycyl peptide fragments such as Boc-Gly-Gly-OH, Boc-Gly-Ser(Bzl)-OCH₃, and related building blocks for subsequent chain elongation or for supply into research and pharmaceutical intermediate markets. Compliance standards in this route include ICH Q3C for residual solvent control, USP <467> for organic volatile impurities, and REACH registration for BOC-Glycine as a phase-in substance. When the active ester is isolated as a dry solid, its storage is limited to −20 °C under argon because the succinimidyl ester hydrolyzes at room temperature with a half-life of less than 48 h at 40% RH. For any specific new fragment, published data for this specific configuration may be limited, so the listed ratios are derived from standard carbodiimide-mediated coupling protocols rather than from a single manufacturer’s technical bulletin.
| Parameter | Specification | Control method |
|---|---|---|
| Reaction solvent water | <0.1% (w/w) | Karl Fischer titration per ASTM E203 |
| Active ester/amino ratio | 1.05–1.20 mol equiv | LC-MS monitoring |
| Activation temperature | 0–5 °C | Brine-cooled jacket |
| Aminolysis time | 6–16 h | HPLC area percent |
| Isolated active ester storage | −20 °C under argon | Stability study at 40% RH |
In antibody-drug conjugate linker construction, BOC-Glycine operates as a protected glycine building block for short, flexible spacer segments between the maleimide-capped terminus and the cathepsin-cleavable valine-citrulline dipeptide. In solid-phase assembly, Boc-Gly-OH is coupled to the resin-bound amino acid at 1.5–3.0 mol equiv relative to the determined free amine loading; activation with HATU and diisopropylethylamine in dimethylformamide at 20–25 °C proceeds for 30–60 min. The coupling solvent is selected to have water <0.05% (w/w) and dimethylamine <10 ppm to prevent premature Fmoc removal when a hybrid Boc-Fmoc strategy is used. Final cleavage from 2-chlorotrityl resin uses a cocktail of TFA/triisopropylsilane/water 95:2.5:2.5 (v/v/v) at 25 °C for 60–120 min. The resulting protected linker intermediate is purified by reversed-phase preparative HPLC with C18 stationary phase and acetonitrile/water gradients containing 0.1% (v/v) TFA, followed by lyophilization to a residual TFA content ≤0.5% (w/w).
Compliance standards for an intermediate intended for ADC conjugation include ICH Q3D for elemental impurities, ICH Q6B for biotechnological products where the intermediate later faces conjugation, FDA 21 CFR 210.1 for current good manufacturing practice, and USP <788> for particulate matter if the final linker is injected as part of a device or formulation. Terminal product types include Boc-protected glycyl-valine-citrulline-PABC intermediates, maleimide-terminated glycyl linkers, and activated carbonate-linked payload-linker constructs. The glycine residue is introduced to tune the solubility of the linker or to adjust the spatial separation between the maleimide moiety and the enzyme-sensitive site. A processing boundary exists after the TFA cleavage step: the acid-labile Boc group is removed during global deprotection, so if a Boc-protected fragment is needed downstream, cleavage must instead be performed with 0.1 M hydrochloric acid in dioxane or with hexafluoroisopropanol to leave the Boc group intact. Published data for this specific configuration is limited for exact molar excess in cGMP ADC campaigns; the quoted 1.5–3.0 eq range is consistent with general SPPS coupling protocols for hindered linker sequences.
Cosmetic oligopeptide manufacturing may select BOC-Glycine as the protected glycine monomer when the downstream peptide is a short glycine-containing sequence for topical application, such as a tetrapeptide or pentapeptide intended for skin conditioning. In solution-phase coupling of BOC-Glycine to a proline or lysine derivative, the addition ratio is 1.05–1.20 mol equiv relative to the amino component; in solid-phase synthesis on Wang resin with substitution 0.5–0.8 mmol/g, the ratio increases to 1.5–3.0 mol equiv with DIC/HOBt activation in dimethylformamide. Coupling is typically performed at 20–25 °C for 45–90 min; if proline is the following residue, the risk of diketopiperazine is reduced by coupling glycine at 4 °C for 2 h and maintaining the resin slurry in a low-water dimethylformamide environment of <0.05% (w/w).
Downstream processing includes precipitation from methyl tert-butyl ether/heptane 1:3 (v/v), washing with 5% (w/v) sodium bicarbonate, and preparative HPLC with ethanol/water mobile phases to keep residual solvents compliant with ICH Q3C. The final product is typically supplied as a lyophilized powder or as a stock solution at 0.1–1.0 mg/mL in a preservative-free buffer. Compliance standards applicable to this segment are EC 1223/2009 Article 10 for cosmetic product safety assessment and Article 15 for nanomaterial notification where relevant, EFfCI GMP for cosmetic ingredient manufacture, and ISO 16128 where deriving a natural-origin index is required. Synthetic peptide ingredients are not natural under ISO 16128 but may be described as nature-identical building blocks under a separate technical dossier. Terminal product types include palmitoyl-modified glycine-containing peptides, copper-complexing glycyl-histidyl-lysine-type peptides, and acetylated oligopeptide powders for formulation into serums or creams.
For fluorogenic substrate manufacturing, BOC-Glycine is converted into protected glycine-7-amino-4-methylcoumarin derivatives used in enzyme activity assays. In a representative solution-phase synthesis, Boc-Gly-OH is activated with EDC/HCl and HOSu in dichloromethane at 0–4 °C; the activated ester is then coupled to 7-amino-4-methylcoumarin at 1.10–1.20 mol equiv in the presence of 1.20–1.50 equiv of N-methylmorpholine. The reaction is complete within 8–16 h at 20–25 °C under argon. The crude product is purified by silica flash chromatography with a gradient of ethyl acetate in n-hexane from 30 to 80% to yield Boc-Gly-AMC. Deprotection with TFA/DCM 1:1 (v/v) exposes Gly-AMC, which is then lyophilized from acetonitrile/water. For diagnostic raw material use, the product is released with residual TFA ≤0.1% (w/w), residual water ≤1.0% (w/w), and HPLC purity ≥98.0% by area at 210 nm.
Compliance standards for diagnostic substrates depend on the intended use: for research-use-only material, ISO 9001 quality management applies; for components supplied into in vitro diagnostic kits, ISO 13485:2016 Section 7.5.1 requires process control and traceability, and ISO 14971 supports risk assessment of raw material changes. Terminal product types include glycine-AMC substrates, Boc-protected peptide-AMC intermediates, and chromogenic glycine-p-nitroanilide derivatives used in protease activity assays. A production boundary exists in the chromatographic purification step: silica gel promotes partial Boc loss on prolonged contact, so the load is limited to 50 mg crude per g silica and acid-washed silica is avoided. Published data for this specific configuration is limited for all diagnostic substrate derivatives, and the ratios above reflect standard carbodiimide-mediated coupling used in laboratory and pilot settings rather than a unified pharmacopeial monograph.
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BOC-Glycine, catalogued as BOC-Gly-OH and specified as N-(tert-butoxycarbonyl)glycine under CAS 4530-20-5, is supplied as a white to off-white crystalline solid with molecular formula C7H13NO4 and molecular weight 175.18 g/mol. The free carboxylic acid function permits direct activation with carbodiimide, uronium, or phosphonium reagents in peptide coupling, while the tert-butoxycarbonyl amino blocking group remains intact under basic, nucleophilic conditions. Because the molecule contains no aromatic chromophore, high-performance liquid chromatography with ultraviolet detection is operated at 205–210 nm, where the carboxyl and carbamate carbonyl groups absorb weakly; the detection limit is lower than that of the Fmoc-protected analogue. A typical lot is released with an HPLC area-percentage purity of ≥99.0%, a melting range of 88–92 °C, and loss on drying ≤0.5% when tested according to USP <731>.
Release documentation for BOC-Glycine includes identity, purity, water, residual solvent, and residue-on-ignition data. Identity is confirmed by Fourier-transform infrared transmission spectroscopy at 4000–400 cm−1; the carbamate carbonyl stretch near 1680–1690 cm−1 and the acid carbonyl stretch near 1720–1730 cm−1 are reference bands. Proton nuclear magnetic resonance spectra show the tert-butyl singlet near 1.40–1.45 ppm and the glycine methylene singlet near 3.90–4.00 ppm. Melting range is determined by the capillary method according to USP <741> at a heating rate of 1 °C/min; the acceptance interval is 88–92 °C. Optical rotation is not applicable because the glycine α-carbon is achiral.
The absence of a strong chromophore makes the HPLC purity method less forgiving than an Fmoc protocol; baseline noise at 205 nm is commonly 2–5 times higher than at 254 nm. Assay by external standard against a certified BOC-Glycine reference material is run on a C18 column of 150 mm × 4.6 mm internal diameter, 5 μm particle size, using 0.1% phosphoric acid and acetonitrile as mobile phase according to USP <621>. The injection concentration is typically 1 mg/mL in acetonitrile/water 50:50; column temperature is controlled at 30 ± 2 °C to keep retention time variability below 1%. With these conditions, a signal-to-noise ratio of 10:1 at 0.1% impurity level is achievable; below that level, evaporative light-scattering detection or charged aerosol detection is used. Water content is measured by coulometric Karl Fischer titration according to USP <921>, Method Ic, with acceptance at ≤0.5%. Residual solvents are determined by headspace gas chromatography according to USP <467>; typical limits for peptide synthesis grade are dichloromethane ≤500 ppm, N,N-dimethylformamide ≤300 ppm, and methanol ≤100 ppm. Residue on ignition is controlled at ≤0.1% by USP <281>. The loss-on-drying procedure uses vacuum at 60 °C for 3 h; drying above 60 °C is not recommended because the melting range begins at 88 °C and the free acid can partially agglomerate. The product should be re-qualified after any exposure to relative humidity above 60%; water uptake above 0.5% changes weighing accuracy on automated solid dispensing systems with 1 mg resolution.
On a solid-phase Boc-benzyl peptide synthesis line using 500 mmol scale MBHA resin with substitution 0.8 mmol/g, BOC-Glycine is dissolved in DMF at 0.4 M and activated with 1.0 equivalent of DIC and 1.0 equivalent of HOBt at 0–5 °C for 5 min before addition to the resin. The slurry is recirculated through a bottom-fritted glass reactor at 5–10 mL/min per gram of dry resin; after 2 h at 25 °C, the Kaiser ninhydrin test should show less than 1% free primary amine. When the resin remains blue, a second coupling with 0.5 equivalents of fresh activated acid is executed rather than extending the first cycle, because the active ester half-life in DMF is shorter than the solid building block’s storage stability. Coupling efficiency can also be limited by aggregation of glycine-rich domains; if a double coupling fails to achieve a negative Kaiser test, the resin is capped with 10% acetic anhydride, 5% pyridine, and 85% DMF (v/v) to block unreacted amines and prevent deletion sequences. Residual HOBt is removed by three DMF washes of 1 min each. Boc removal is then performed with 95:2.5:2.5 TFA/water/triisopropylsilane for 30 min at 25 °C. Residual TFA from the deprotection step is neutralized before the next coupling using 5% DIPEA in DMF for 3 × 1 min; incomplete neutralization protonates the resin-bound amine and reduces the subsequent coupling yield.
The orthogonal behaviour of BOC-Glycine arises from the acid-catalysed fragmentation of the tert-butyl carbamate to isobutylene, carbon dioxide, and the free amine. Under basic conditions, piperidine does not cleave the Boc group at ambient temperature; 20% piperidine in DMF at 25 °C for 20 min is a standard Fmoc deprotection condition to which BOC-Glycine remains largely intact. The Cbz group requires hydrogenolysis over palladium or strongly acidic cleavage. This orthogonality allows BOC-Glycine to serve as a temporary N-terminal building block in Fmoc/tBu systems, where final TFA cleavage simultaneously removes the Boc group. However, the free carboxyl group of BOC-Glycine in 1 M aqueous sodium hydroxide forms the sodium carboxylate and can contribute to hydrolysis of base-sensitive esters elsewhere; therefore BOC-Glycine is not considered fully base-inert in all process settings. Acidolysis with 4 M HCl in dioxane at 25 °C or 95:2.5:2.5 TFA/water/triisopropylsilane is used for complete Boc removal. In TFA/DCM systems, tert-butyl cation is generated and is scavenged by added triisopropylsilane or anisole to suppress alkylation of electron-rich side chains. Because the glycine residue has no electron-rich side chain, BOC-Glycine itself presents a lower alkylation risk than Boc-protected tryptophan or methionine building blocks. The free amine liberated after acidolysis can be converted to an ammonium salt; coupling must therefore follow neutralization or be performed in a separate pot after solvent exchange into DMF.
In solution-phase peptide synthesis, BOC-Glycine is coupled to amino acid methyl esters using EDC hydrochloride and HOBt in dichloromethane at 0 °C. Workup with 0.5 M citric acid and 0.5 M sodium bicarbonate is followed by rotary evaporation at 35 °C and 80 mbar. When the amino acid ester is proline or sarcosine, diketopiperazine formation after N-deprotection is significant if the pH during neutralization exceeds 7.5; the cyclization is suppressed by keeping the neutralization temperature at 0–5 °C and coupling immediately. The glycine residue is achiral, so epimerization during carboxyl activation is not a controlling variable. This is a major difference from BOC-protected L-amino acids, where oxazolone-mediated epimerization can compromise enantiomeric purity. Coupling completion is assessed by HPLC conversion of the amino acid ester peak area according to USP <621>; incomplete conversion below 95% warrants a second activation with 0.3 equivalents of EDC hydrochloride. For conversion to BOC-Gly-OSu, BOC-Glycine is treated with N-hydroxysuccinimide and DCC in DMF at 0 °C for 12 h; dicyclohexylurea is removed by filtration and the active ester is precipitated by addition of cold hexane. The resulting active ester is hygroscopic and must be dried under vacuum at 25 °C to a water content below 0.5%.
BOC-Glycine is selected instead of Fmoc-Glycine when a downstream intermediate contains a base-sensitive ester, a β-elimination-prone side-chain protecting group, or an aspartimide-prone Asp-Gly sequence. Fmoc removal with 20% piperidine in DMF at 25 °C for 20 min is an efficient deprotection step, but repeated exposure in a 20-cycle synthesis increases cumulative base burden and can accelerate hydrolysis of C-terminal methyl esters when water content in piperidine/DMF exceeds 0.1%. Boc chemistry replaces repeated piperidine exposure with repeated TFA exposure; this is not universally superior, because TFA can acidolyse sensitive side-chain protecting groups and release resin-bound peptide early in Boc-SPPS. The process choice therefore depends on the sequence-specific degradation profile. For a base-sensitive C-terminal ester, BOC-Glycine may allow shorter total base contact and is removed with acid, preserving the ester. In that configuration, inline UV monitoring at 301 nm is not available for the Boc-protected glycine; off-line HPLC at 205 nm or Kaiser testing is required to confirm coupling. Stress stability comparisons are performed by spiking the protected intermediate with 20% piperidine at 25 °C for 24 h and measuring degradation by HPLC according to USP <621>. A base-sensitive C-terminal benzyl ester should not be exposed to 1 M sodium hydroxide during aqueous workup of BOC-Glycine couplings; alternative extraction with 0.5 M citric acid and saturated sodium bicarbonate is used with pH controlled at 7.2–7.5.
Long-term storage of BOC-Glycine is specified at 2–8 °C in a desiccated amber glass container under inert gas. The material is commonly packaged in 25 g, 100 g, and 1 kg amber glass bottles with polypropylene closures; bulk quantities above 10 kg are supplied in double polyethylene liners inside fibre drums. Headspace oxygen is displaced with nitrogen to below 1% residual oxygen before sealing. Packaging contact materials are selected to avoid leachable amines or metal salts that could desorb into the product. After a container is opened, the hygroscopic free acid absorbs moisture if relative humidity exceeds 60%; the resulting water uptake produces clumping and a loss of weighing accuracy on automated solid dispensing systems with 1 mg resolution. For use in anhydrous coupling reactions, the material is re-dried under vacuum at 40 °C and 10 mbar for 12 h if Karl Fischer water content exceeds 0.5%. Stability studies following ICH Q1A guidance can be used to assign shelf life, but published data for extended storage above 40 °C and 75% relative humidity is limited; accelerated testing above 80 °C should be interpreted with caution because the melting range begins at 88 °C and physical form changes. The compound should not be stored in contact with strong acids, acid chlorides, or oxidizing agents. Incompatibility with amine-based additives is not general, because the Boc group is stable to amines; however, in the presence of a carbodiimide activating agent, free amines in the reaction mixture compete with the desired nucleophile and consume the activated carboxyl function.
Table 1 summarizes orthogonal removal conditions and analytical detection differences among three widely used N-protected glycine reagents. These differences affect process selection, analytical monitoring, and waste-stream handling.
| Parameter | BOC-Glycine | Fmoc-Glycine | Cbz-Glycine |
|---|---|---|---|
| CAS registry number | 4530-20-5 | 29022-11-5 | 1138-80-3 |
| Molecular weight | 175.18 g/mol | 297.31 g/mol | 209.20 g/mol |
| Primary removal condition | 4 M HCl/dioxane or 95:2.5:2.5 TFA/water/triisopropylsilane | 20% piperidine/DMF | H2/Pd-C or HBr/AcOH |
| UV detection | 205–210 nm weak carbonyl | 301 nm strong Fmoc chromophore | 254 nm weak benzyl chromophore |
| Base stability | Stable to piperidine; carboxyl salt formation in aqueous base | Labile to piperidine | Stable to piperidine |
| Acid stability | Labile to TFA/HCl | Stable under mild acid | Stable under mild acid |
| Typical HPLC release purity | ≥99.0% | ≥99.0% | ≥99.0% |
BOC-Glycine differs from its pre-activated N-hydroxysuccinimide ester, BOC-Gly-OSu, in hydrolytic sensitivity and activation control. The free acid is less sensitive to atmospheric moisture and is suitable for large-scale in situ activation; the isolated active ester couples rapidly at 0–25 °C but must be stored at −20 °C under desiccation. In continuous-flow peptide synthesis with a residence time of 10–20 min, the pre-activated ester can complete acylation within 15 min, whereas the free acid may require a separate activation loop. Since BOC-Glycine has no strong chromophore above 250 nm, process analytical technology relying on inline UV at 280–300 nm will not detect it; refractive index or charged aerosol detectors are required for continuous monitoring. Acidolytic Boc removal generates isobutylene gas and a strongly acidic waste stream that requires neutralization before discharge; piperidine-based Fmoc removal generates alkaline waste, and Cbz removal over palladium requires catalyst recovery from hydrogen-saturated solvents. The selection between BOC-Glycine, Fmoc-Glycine, and Cbz-Glycine therefore depends on the cleavage regime, detector availability, waste-stream infrastructure, and the sequence-specific tolerance to acid or base.
