Enol ethers intramolecular hydrosilylation

This intramolecular hydrosilylation can be extended to a-hydroxy enol ethers (2-alkoxy-l-alkene-2-ols) to provide access to 2,3-sy -l,2,3-triols.2 In this case a neutral catalyst, Pt(0)-vinylsiloxane,3 is preferred over H2PtCl6. 

Tamao, K. Nakagawa, Y. Ito, Y. Regio- and stereoselective intramolecular hydrosilylation of a-hydroxy enol ethers 2,3-syn-2-methoxy-methoxy-l,3-nonanediol. Org. Synth. 1998,... 

REG 10- AND STEREOSELECTIVE INTRAMOLECULAR HYDROSILYLATION OF a-HYDROXY ENOL ETHERS 2,3-syn-2-METhOXYM ETHOXY-1,3-NON ANEDIOL (1,3-Nonanedlol, 2-(methoxymethoxy)-, (R, R )-( )-)... 

In an extension of this process, the intramolecular hydrosilylation of a-hydroxy enol ethers has been presented as a new, syn selective route to 1,2,3-triols (Scheme 11). With such sensitive substrates, a neutral hydrosilylation catalyst, Pt [(CH2==CH)Me2Si]20 2, must be used. The utility of this method has been demonstrated in a synthesis of the pentitols, o-arabinol and xylitol (as their pentaacetates), in optically pure form. 

---