8-Lanosten-24-one was converted into 8-lanosten-23-one by carbonyl transposition via 23,23-dimethoxy-8-lanosten-24-one without degradation and reconstruction of the side chain. By the same procedure 29-nor-9(11)-lanosten-24-one was transformed into the corresponding 23-one.
As authentic samples for identification of 29-norlanostane derivatives isolated from plant fossil, 29-norlanostan-24-one and -23-one, 29-norlanost-9(11)-en-24-one, -23-one, and -3-one, 29-norlanost-7-en-3-one, and 29-norlanostan-3-one were synthesized from a commercial lanosterol containing dihydrolanosterol.