Conditions for metalation of a variety of cyclic vinylethers and reaction of the resulting carbanions with electrophiles are described. Effects of the vinylether structure on the relative rates of metalation are discussed. Applications of this methodology to the construction of various types of carbonyl compounds are presented.
A reductive cyclization strategy was applied to the synthesis of attenol A. This nontraditional approach to the spiroacetal structure illustrated several advantages of the reductive cyclization methodology. The attenol A core was formed in a carbon-carbon bond coupling that gave rise to a previously inaccessible spiroacetal epimer, a new method to synthesize thioketene acetals from a phenyl sulfone was realized, and the configurational stability of a nonanomeric spiroacetal was evaluated. A minor byproduct in the reductive cyclization reaction was identified that for the first time allowed direct evaluation of the stereoselectivity in a reductive cyclization of a dialkyloxy alkyllithium reagent.
BOECKMAN, R. K. ,, JR;BRUZA, K. J., TETRAHEDRON, 1981, 37, N 23, 3997-4006
作者:BOECKMAN, R. K. ,, JR、BRUZA, K. J.
DOI:——
日期:——
CRICH, DAVID;RITCHIE, TIMOTHY J., TETRAHEDRON, 44,(1988) N 8, 2319-2328
作者:CRICH, DAVID、RITCHIE, TIMOTHY J.
DOI:——
日期:——
Application of Hemithio Ketene Acetals to the Synthesis of Spirocyclic Orthoesters
作者:Scott Rychnovsky、Thomas La Cruz
DOI:10.1055/s-2004-830874
日期:——
Spirocyclic orthoesters have been synthesized by a method that employs a hemithiophenyl keteneacetal as an orthoester precursor. The orthoesters can be generated in good yields and under mild reaction conditions.