Fujishima T1, Kittaka A, Kurihara M, Saito N, Honzawa S, Kishimoto S, Sugiura T, Waku K, Takayama H.
J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):89-92.All four possible A-ring stereoisomers of 2,2-dimethyl-1,25-dihydroxyvitamin D(3) (4) were designed and convergently synthesized. Nine-step conversion of methyl hydroxypivalate 6 provided the desired A-ring enyne synthon (13a,b) in good overall yield. Cross-coupling reaction of the A-ring synthon 13a,b with the CD-ring portion in the presence of palladium catalyst, followed by deprotection, gave the vitamin analogues (4a-d). Read More