Jmg. Galvez et al., ENANTIOSELECTIVE SYNTHESIS OF SPIRO[4.5]DECANONE WITH 2-(S)-METHOXY-1,4-DIBROMOBUTANE, Tetrahedron letters, 35(18), 1994, pp. 2849-2852
The reaction of 3-methyl-2-cyclohexen-1-one with 2-(S)-methoxy-1,4-dib
romobutane (2) produced spiro[4.5]decanone 3, a key intermediate for t
he synthesis of spirovetivanes, with regiodifferentiation and stereose
lection. Subsequent addition of diisopropoxydimethyltitanium to the ca
rbonyl group furnished compound 6 with diasterofacial selectivity. The
same selectivity was observed in the subsequent catalytic hydrogenati
on.