A C-B-A-D approach to brassinosteroids; obtention of a C-ring precursor from pyridine

Article abstract of DOI:10.1016/S0040-4039(00)76707-4

The potassium salt of glutaconaldehyde, a degradation product of pyridine, has been converted, via inter alia IMDA cyclisation of a dienyl fumaric ester and baker's yeast-mediated reduction of a ketoester, into an optically-active 2,3,4-trisubstituted cyc