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Fmoc-L-4-Nitro-Phe-OH (N-α-fluorenylmethoxycarbonyl-4-nitro-L-phenylalanine) is a high-purity L-configuration, Fmoc-protected phenylalanine derivative featuring an electron-withdrawing nitro group at the para position of the aromatic ring. As the naturally occurring enantiomer of phenylalanine, the L-configuration maintains the stereochemical orientation found in proteins and native peptides, making Fmoc-L-4-Nitro-Phe-OH the preferred building block for the synthesis of bioactive peptides that retain native conformational and functional properties.

Fmoc-D-Phe-OH (N-[(9H-Fluoren-9-ylmethoxy)carbonyl]-D-phenylalanine, molecular formula C₂₄H₂₁NO₄) is an N‑Fmoc‑protected form of the non‑natural D‑enantiomer of the aromatic amino acid phenylalanine. Structurally, the molecule consists of a 9‑fluorenylmethyloxycarbonyl (Fmoc) group attached to the α‑amino nitrogen of D‑phenylalanine via a carbamate linkage, with a free carboxylic acid at the C‑terminus. The Fmoc group is orthogonal to acid‑labile side‑chain protecting groups and is rapidly cleaved under mild basic conditions (typically 20% piperidine in DMF), without affecting the integrity of growing peptide chains or the Wang/Trt resin linkage.

Fmoc-Cys(Acm)-OH (N-α-Fmoc-S-acetamidomethyl-L-cysteine) is an orthogonally protected cysteine derivative where the thiol group is masked by the acetamidomethyl (Acm) protecting group and the α-amino function is protected by the 9-fluorenylmethyloxycarbonyl (Fmoc) group. The Acm protection is stable to trifluoroacetic acid (TFA), enabling the selective deprotection of cysteine thiols during Fmoc solid-phase peptide synthesis without exposing the peptide to the acidic cleavage conditions required for standard side-chain protecting groups.

Fmoc-Gly-OH (N-9-fluorenylmethoxycarbonylglycine) is the simplest Fmoc-protected amino acid building block. The Fmoc group protects the α-amino function of glycine, allowing its incorporation into peptide chains in Fmoc SPPS. As the smallest and most conformationally flexible amino acid, glycine introduces no side-chain steric hindrance, allowing Fmoc-Gly-OH to be efficiently coupled in all positions of a peptide sequence with minimal risk of racemization.

The product is Fmoc-Pro-OH (N-[(9H-Fluoren-9-ylmethoxy)carbonyl]-L-proline, also known as Fmoc-L-proline), a cornerstone building block in modern peptide synthesis. Structurally, the molecule features a bicyclic proline residue — uniquely incorporating a secondary amine as part of a rigid pyrrolidine ring — protected at its N-terminal by the base-labile 9-fluorenylmethyloxycarbonyl (Fmoc) group, which serves as the gold-standard amine protecting group in solid-phase peptide synthesis.

The product Fmoc-N-Methyl-L-Val-OH (IUPAC: N-[(9H-fluoren-9-ylmethoxy)carbonyl]-N-methyl-L-valine, also known as Fmoc-N-Me-Val-OH) is a specialized N-α-Fmoc protected derivative of N-methyl-L-valine. The molecule is built upon the branched aliphatic side chain of valine, but the defining structural modification is the substitution of the backbone amide hydrogen with a methyl group at the nitrogen atom.