Platinum(II) Salt Catalyzed Annulation of Hydroxyalkyl-Substituted ­Vinylsilanes with Aldehydes

Abstract

In the presence of catalytic amounts of PtCl₂ and AgX (X = OTf or SbF₆), (Z)-6-trimethylsilyl-5-hexen-1-ol and (Z)-5-trimethylsilyl-4-penten-1-ol reacted smoothly with aldehydes to give 2,3-disubstituted tetrahydropyrans and tetrahydrofurans, respectively, in good to high yields. The reaction mechanism involves the isomerization of the starting vinylsilanes to the corresponding allylsilanes and subsequence Prins-type annulation with aldehydes.

Key words

aldehydes - annulations - catalysis - silicon - tandem reactions

References

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9

As a preliminary result, we found that the PtCl₂-catalyzed (5 mol%) reaction of 2 with 3e gave 4e (45 °C, 24 h, 24% yield) although the conditions were not optimized.

10

For the origin of stereoselective formation of trans-4 and cis-8, see ref. 3b,f and ref. 3a, respectively.