Scope and facial selectivity of the Prins-pinacol synthesis of attached rings

Using a B-alkyl Suzuki cross-coupling as a key step, a concise and stereocontrolled synthesis of five- to eight-membered triisopropylsiloxy ethers having (2Z)-(6,6-dimethoxyhexylidene) or (2Z)-(5,5-dimethoxypentylidene) side chains was developed. Prins-pinacol reactions of these precursors promoted by SnCl4 provide bicyclic products in which 5-, 6-, or 7-membered rings are joined by a C-C single bond. Synthetically challenging attached ring systems in which both rings are chiral can be prepared in this fashion with high stereo- and enantioselectivity. Stabilizing through-space electrostatic interactions between the alpha-alkoxycarbenium ion and an axially positioned oxygen substituent are believed to play a significant role in organizing the transition structure of the Prins cyclization.     

Stereocontrolled construction of either stereoisomer of 12-oxatricyclo[6.3.1.0(2,7)]dodecanes using Prins-pinacol reactions

[reaction: see text] 12-Oxatricyclo[6.3.1.0(2,7)]dodecanes can be efficiently synthesized in a stereoselective manner by Prins-pinacol reactions. By biasing the transition state of the Prins cyclization, it is possible to access either stereoisomer of this oxatricyclic ring system.     

On <Emphasis Type="Italic">g</Emphasis>-functions for Laguerre function expansions of Hermite type

We examine weighted L ^p boundedness of g-functions based on semigroups related to multi-dimensional Laguerre function expansions of Hermite type. A technique of vector-valued Calderón–Zygmund operators is used.