N-Fmoc-L-leucine, commonly known as Fmoc-Leu-OH and identified by CAS number 35661-60-0, is a pivotal molecule in modern organic and medicinal chemistry. Its primary significance lies in its role as a protected amino acid derivative, indispensable for the synthesis of peptides through the widely used Fmoc solid-phase peptide synthesis (SPPS) methodology.

The synthesis of Fmoc-Leu-OH typically involves the reaction of L-leucine with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) under controlled conditions. This reaction introduces the base-labile Fmoc protecting group onto the alpha-amino nitrogen of leucine. The resulting compound, Fmoc-Leu-OH, possesses the chemical formula C21H23NO4 and a molecular weight of 353.41. It is usually presented as a white to off-white crystalline powder and exhibits solubility in polar organic solvents such as DMSO and DMF, common characteristics for such chemical intermediates.

The principal application of Fmoc-Leu-OH is in peptide synthesis. As a key building block, it allows for the systematic elongation of a peptide chain. The Fmoc group can be readily cleaved under mild basic conditions, typically with piperidine, revealing a free amine ready for the next coupling reaction. This orthogonal protection strategy is fundamental to Fmoc SPPS, ensuring high yields and purity of synthesized peptides. Researchers rely on the consistent quality of N-Fmoc-L-leucine for creating peptides used in drug discovery, biochemical assays, and materials science.

Beyond its primary role in peptide synthesis, Fmoc-Leu-OH also serves as a valuable chiral building block in broader chemical and biological research. Its defined stereochemistry and functional groups make it a useful starting material for synthesizing various complex organic molecules and analogs. The availability of well-characterized amino acid derivatives for research is crucial for the advancement of scientific understanding and the development of new compounds with potential therapeutic benefits.

When sourcing this critical reagent, researchers emphasize the importance of purity and reliability. Suppliers of peptide synthesis reagents often provide Fmoc-Leu-OH with specified purity levels, typically above 98%, along with comprehensive analytical data such as HPLC and NMR spectra. Adherence to good manufacturing practices ensures that the CAS 35661-60-0 chemical properties meet the stringent requirements of research and pharmaceutical applications. The ability to obtain this compound from trusted N-protected amino acids suppliers ensures the integrity of experimental outcomes.

In summary, Fmoc-Leu-OH (CAS 35661-60-0) is an indispensable reagent that underpins significant advancements in peptide synthesis and related chemical research. Its well-defined synthesis, crucial chemical properties, and diverse applications solidify its position as a vital tool for scientists worldwide.