REACTIONS OF KETALS AND ACETALS WITH (CO)5MNSI(CH3)3 - A NEW VINYL ETHER SYNTHESIS

The reaction of (CO) 5 MnSi(CH 3 ) 3 (1; 1.02.4 equiv, 24 h, 50C, acetonitrile) with ten different methyl ketals(Table I) gives methyl enol ethers in 56% to >95% yields. Easily removed byproducts CH 3 OSi(CH 3 ) 3 and (CO) 5 MnH (or Mn 2 (CO) 9 (CH 3 CN)/Mn 2 (CO) 10 ) also form. When regio- and/or geometric isomers are possible, thermodynamic mixtures are obtained. The reaction of 1 with acetais is more complex, but when conducted under 200 psi of CO, manganese acyls (CO) 5 MnCOCH(OR)R (derived from alkyl intermediates) can be isolated. A general mechanism is proposed in which a ketal or acetal oxygen is initially silylated by 1. Also, 1 rapidly converts cyclohexanone ethylene glycol ketal to [formula omitted] (7) and slowly transforms cyclohexanone diallyl ketal to 1-cyclohexenyl allyl ether. Ortho ester CH 3 C(OCH 3 ) 3 and 1 react to give principally CH 3 CO 2 CH 3 and CH 3 OSi(CH 3 ) 3 . 1982, American Chemical Society. All rights reserved.

REACTIONS OF KETALS AND ACETALS WITH (CO)5MNSI(CH3)3 - A NEW VINYL ETHER SYNTHESIS Academic Article