A. Furstner et al., Ring-closing alkyne metathesis. Application to the total synthesis of sophorolipid lactone, J ORG CHEM, 65(25), 2000, pp. 8758-8762
The first total synthesis of a major component of the microbial biosurfacta
nt sophorolipid has been achieved. This approach-to the 26-membered macroli
de 1 containing a Z-configured alkene group in its lipidic tether spanning
the sophorose backbone is based on a ring-closing metathesis reaction of di
yne 21 catalyzed by Mo[N(t-Bu)(Ar)](3) (5; Ar = 3,5-dimethylphenyl) activat
ed in situ by CH2-Cl-2, followed by Lindlar reduction of the resulting cycl
oalkyne 22. The two beta -glycosidic linkages of compound 21 were installed
by means of the glucal epoxide method and a modified Koenigs-Knorr reactio
n promoted by AgOTf/lutidine, respectively.