Mechanistic and computational studies of exocyclic stereocontrol in the synthesis of bryostatin-like cis-2,6-disubstituted 4-alkylidenetetrahydropyrans by Prins cyclization.

ABSTRACT: The Prins cyclization of syn-?-hydroxy allylsilanes and aldehydes gives cis-2,6-disubstituted 4-alkylidenetetrahydropyrans as sole products in excellent yields regardless of the aldehyde (R?) or syn-?-hydroxy allylsilane substituent (R') used. By reversing the R? and R' groups, complementary exocyclic stereocontrol can be achieved. When the anti-?-hydroxy allylsilanes are used, the Prins cyclization gives predominantly cis-2,6-disubstituted 4-alkylidenetetrahydropyrans, now with the opposite olefin geometry in excellent yield. The proposed reaction mechanism and the observed stereoselectivity for these processes are supported by DFT calculations.

SUBMITTER: Ogawa Y 

PROVIDER: S-EPMC3537866 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature