エステル化・スルホニル化・アミド化・シリル化 : 汎用反応の実用的合理化

抄録

Esterification, sulfonylation, amide formation, and silylations are well recognized as frequently used reactions for organic syntheses. Recent syntheses of fine chemicals and complex natural products, however, require further rationalization of these reactions. We describe herein our recent studies in this area including related representative known methods.
(i) Recent progresses of catalytic esterifications are surveyed and we introduce two efficient ammonium triflate catalysts (DPAT and PFPAT) for esterification between 1 : 1 mixture of carboxylic acids and alcohols. (ii) Conventional condensation reagents for esterifications, thioesterifications, and amide formation, are listed and we introduce efficient methods using Me₂NSO₂Cl/ Me₂NR and p-TsCl/N-methylimidazole. (iii) As a promising method for the replacement of conventional pyridine-method, we introduce efficient pyridine-free improved methods, which utilize sterically uncrowded tertiary amines such as Me₃N·HCl/Et₃N and Me₂N (CH₂) _nNMe₂ as a key protocol. (iv) We introduce highly powerful, neutral, and catalytic methods for silylations of alcohols (giving enol ethers) and ketones (giving enol silyl ethers) using hydrosilanes, disilanes, and silazanes.