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Synlett 2005(12): 1960-1961  
DOI: 10.1055/s-2005-871948
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

Polymethylhydrosiloxane (PMHS)

Kula Kamal Senapati*
Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, Pin-784028, India
e-Mail: kksena@tezu.ernet.in;
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Publication History

Publication Date:
07 July 2005 (online)

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Introduction

Polymethylhydrosiloxane (PMHS), a silicon industry by-product [1] incorporating with various catalysts including Sn, Ti, Pd, Zn, Zr and Cu, is found to be effective as an ­excellent alternative reducing agent in organic synthesis. It is inexpensive, commercially available, non-toxic, biodegradable and stable to air and moisture, which makes it an attractive reagent of choice. The reagent is of low ­viscosity and soluble in most organic solvents. [2]

Besides its recognized application in chemoselective as well as regioselective [3] reductions, it finds uses in ­asymmetric reduction of different species such as acetophenones [4] and benzophenone derivatives, [5] imines, [6] and conjugated double bonds. [7a] [b]

In catalytic reduction processes using PMHS in combination with metal catalysts, the catalysts play the role as ­hydride transferring agents. [2] [8] Some nucleophiles like fluoride [1] [8] [9] also act as catalyst in addition to metals.

Being a convenient chemoselective reagent for different ketones, imines and phosphine oxides, it has also been used in reductive cleavage of carbon-halogen [1] [9] as well as carbon-sulfur bonds.1