Mukaiyama Aldol-Prins Cyclizations with Ketones

Abstract

The Mukaiyama aldol-Prins (MAP) cyclization with ketones is described. These reactions produce substituted tetrahydropyrans efficiently and in some cases with high stereoselectivity. Cyclizations with E- and Z-alkenes are shown to be stereospecific. These studies extend the scope of the MAP cyclizations promoted by titanium tetrabromide.

tandem reactions - annulations - aldol reaction - stereo­selective - carbocations

References

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Related cascade cyclizations:

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Preparations of ketones in Table 1:

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9

The configurations of the stereocenters in 8 and 9 were determined by analysis of the ¹H NMR coupling constants and of the NOESY spectra.