The ISMS condensation of allylsilane 4 does not follow the expected pathway but rather leads to an efficient synthesis of trisubstituted and tetrasubstituted tetrahydropyran derivatives.
Marko, I., & Bayston, DJ. (1993). The Intramolecular Silyl-modified Sakurai (isms) Reaction - Stereoselective Preparation of Tri-substituted and Tetra-substituted Tetrahydropyrans. Tetrahedron Letters, 34(41), 6595-6598. https://doi.org/10.1016/0040-4039(93)88114-X (Original work published 1993)