Vanadyl acetoacetate

I.POXIDATION, ASYMMETRIC (--)-Benzylquininium chloride. f-Butyl hydroperoxide-Vanadyl acetoacetate. Hydrogen peroxide-1,1,3,3-Tetrachloro-aceione. (SM2-Hydroxy-N,N-diinethyl-propanamidc-OtO )oxodiperoxymolyb-denum(VI). 

Reagents i, H2 Lindlar catalyst ii, Bu 02H-vanadyl acetoacetate iii, LIA1H4. 

Although direct oleflnation of l,4-dien-3-ones is synthetically difficult, an indirect route is now available conversion of the carbonyl to the propargyl alcohol, followed by catalytic Meyer-Schuster rearrangement using vanadyl acetoacetate [VO(acac)2]. Asymmetric alkoxyallylation of aldehydes has been achieved using a combined carbocupration-zinc homologation-allylation reaction in one pot. ... 

The acetylenic side chain of (58) has been hydrogenated in the presence of Lindler catalyst to give the Z-allylic alcohol (70). This olefin was stereoselectively epoxidized at -78° with t-butyl hydroperoxide and a catalytic amount of vanadyl acetoacetate to give an 85 15 mixture of products (71) and (72). The major isomer (71) was separated and converted to 24(R),25-dihydroxycholesterol (73) by the subsequent steps of lithium aluminum hydride reduction and A-ring depfotection (143). These steps provide the means for selectively preparing 24,25-dihydroxy-vitamin D compounds with the natural configuration at the 24-position. 

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