A three-step synthesis of (2Z), (4E)-polyenic acids 6 is described. Condensation of aldehydes 1 with potassium prenal enolate led to dihydropyranols 3 which were oxidized into dihydropyrones 5, precursors of (2Z), (4E)-polyenic acids 6. The procedure was applied to a synthesis of 13-cis-retinoic acids from beta-ionylidene acetaldehydes. (C) 2000 Elsevier Science Ltd. All rights reserved.
Regioselective addition of the prenal potassium dienolate onto α,β-unsaturated aldehydes. A short access to polyenaldehydes
The potassium dienolate of prenal obtained by treatment of the corresponding dienoxysilane with tBuOK was reacted with enaldehydes. In all cases a gamma-specific reaction occurs. According to the reaction conditions gamma;1,2 or a gamma;1,4 coupled product was selectively obtained with enals. The gamma;1,2 reaction provided an efficient prenylation procedure. A short two-step synthesis of retinal is described. (C) 1998 Elsevier Science Ltd. All rights reserved.
US5157133A
申请人:——
公开号:US5157133A
公开(公告)日:1992-10-20
US5250710A
申请人:——
公开号:US5250710A
公开(公告)日:1993-10-05
A new prenylation method using the lithium enolate of prenal. Reaction with polyunsaturated aldehydes. A short access to retinal.
The enolate of prenal 1 prepared from the corresponding silyl enolether 2 or enol acetate 3 led to a γ-regiospecific reaction with polyunsaturated aldehydes 4 yielding dihydropyrans 5 leading after hydrolysis to polyenals 7. This process allows the introduction of the isoprenyl skeleton. A synthesis of retinal. from β-ionylidenacetaldehyde is reported.