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Synfacts 2005(3): 0319-0319  
DOI: 10.1055/s-2005-916140
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Catalytic Prins Cyclization using In(OTf)3 and Silyl Additives

Contributor(s): Mark Lautens, Josephine Yuen
K.-P. Chan, T.-P. Loh*
Nanyang Technological University, Singapore
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Publication History

Publication Date:
22 November 2005 (online)

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Significance

Use of a catalytic amount of In(OTf)3 (5 mol%) and trimethylsilyl halides gave a highly diastereoselective Prins cyclization. Reduced epimerization was achieved by using a weaker Lewis acid, In(OTf)3 and also TMSBr as additive which also acts as the halide source. Excellent diastereoselectivity for the 2,4,6-trisubstituted tetrahydropyran products were observed.