10.1021/jo00392a044
The research focuses on the synthesis and reaction of chiral aldehydes with specific reagents to study diastereofacial selectivity. The purpose is to explore the factors controlling aldehyde facial selectivity using crotyldiisopinocampheylboranes (13-16) with chiral aldehydes (17 and 18). The reactions were highly stereoselective, yielding products with high facial selectivities. The study concludes that the chirality of the reagent controls the overall diastereofacial selectivity in the reaction, allowing access to all possible stereoisomers in high optical purity by selecting the proper antipode of the reagents and aldehydes. This method could be a convenient route for synthesizing macrolide and polyether antibiotics. (S)-2-Methylbutanal and (S)-2-(benzyloxy)propanal are chiral aldehydes used as reactants to study diastereoselectivity.
10.1055/s-2003-37129
The research aims to develop a stereoselective synthesis method for methyl (–)-nonactate, a key component in the production of nonactin, an antibiotic ionophore used in ion selective electrodes. The study explores the influence of olefin geometry on the stereoselectivity of iodoetherification, a crucial step in the synthesis. Key chemicals used include (E)-?-triethylsilyloxyalkene, generated from sulfone and (S)-2-benzyloxypropanal, which undergoes intramolecular iodoetherification in the presence of silver carbonate to form the key intermediate, cis-2,5-disubstituted tetrahydrofuran. (S)-2-benzyloxypropanal plays a pivotal role as a key reactant in the stereoselective synthesis process. It is used in the formation of (Z)-?-triethylsilyloxyalkene through a Wittig olefination reaction with phosphonium salt, which is derived from an alcohol intermediate. The researchers found that the geometry of the olefin significantly affects the stereoselectivity of the iodoetherification process, with trans-olefins yielding higher stereoselectivity. The study concludes that by carefully controlling the olefin geometry and using silver carbonate as a catalyst, a highly stereoselective synthesis of methyl (–)-nonactate can be achieved, paving the way for further total synthesis of nonactin.
