RESUMEN
The 20-membered marine macrodiolide clavosolideâ A is prepared in 7 steps (LLS) in the absence of protecting groups or chiral auxiliaries via enantioselective alcohol-mediated carbonyl addition. In 9 prior total syntheses, 11-34 steps (LLS) were required.
Asunto(s)
Alcoholes/química , Compuestos Alílicos/síntesis química , Macrólidos/síntesis química , Policétidos/química , Compuestos Alílicos/química , Macrólidos/química , Estructura Molecular , EstereoisomerismoRESUMEN
Enantioselectivity increases with increasing carbonyl electrophilicity in 2-propanol-mediated reductive couplings of aldehydes with branched aryl-substituted allylic acetates to form products of carbonyl anti-(α-aryl)allylation. This unusual phenomenon is caused by aldehyde coordination to diastereomeric kinetic vs thermodynamic carbonyl binding sites that deliver enantiomeric products. Exploiting this effect, anti-diastereo- and enantioselective (α-aryl)allylations of fluoral hydrate and difluoroacetaldehyde ethyl hemiacetal were developed.
Asunto(s)
Acetaldehído/análogos & derivados , Acetales/síntesis química , Compuestos Alílicos/síntesis química , Derivados de Atropina/síntesis química , Iridio/química , 2-Propanol/química , Acetaldehído/química , Acetatos/química , Catálisis , Cinética , Oxidación-Reducción , Estereoisomerismo , TermodinámicaRESUMEN
An inside job: Enantioselective phthalide synthesis was achieved through internal redox allylation of o-phthalaldehydes. Oxidative esterification is balanced by reductive carbonyl addition to achieve an overall redox-neutral process. This method enabled formal syntheses of ent-spirolaxine methyl ether and CJ-12,954.
Asunto(s)
Benzofuranos/química , Iridio/química , o-Ftalaldehído/química , Catálisis , Esterificación , Hidrogenación , Oxidación-Reducción , EstereoisomerismoRESUMEN
Several Gold's reagents were synthesized from cyanuric chloride and N,N-dialkylformamides. These synthetic equivalents of N,N-dimethylformamide dimethyl acetal were used in an optimized and scalable procedure for the regioselective synthesis of a variety of enaminones from ketone starting materials, whose utility was demonstrated by the stereoselective synthesis of Rawal-type dienes.
