Cobryketone derived from vitamin B12 via palladium-catalyzed cleavage of the sp3-sp3 carbon-carbon bond.

Sylwester Kurcoń, Keith ó Proinsias, Dorota Gryko

Index: J. Org. Chem. 78(8) , 4115-22, (2013)

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Abstract

Heptamethyl cobyrinate was transformed into hexamethyl 8-nor-cobyrinate. The crucial step involved the synthesis of new, vitamin B12 derived cobryketone via palladium-catalyzed cleavage of the sp(3)-sp(3) carbon-carbon bond with the liberation of the ketone. The replacement of sp(3) carbon atom with sp(2) (C═O) at the 8-position produces a bathochromic shift of all absorption bands and makes α and β bands equal as a consequence of the expansion of the existing conjugated system of double bonds.