Mj. Chen et al., Total synthesis of (+)-blastmycinone, (-)-litsenolide C-1, and related natural trisubstituted lactones via alkynyltungsten compounds, J ORG CHEM, 65(20), 2000, pp. 6362-6367
A general method for total synthesis of natural trisubstituted gamma-lacton
es is developed on the basis of the chemistry of alkynyltungsten compounds.
The key step in this approach involves the cycloalkenation of tungsten-eta
(1)-(3R,4S)-pent-1-yne-3,4-diol with aldehydes to give;tungsten-oxacarbeniu
m salts, further leading to 3-alkylidene-4-hydroxy-5-methyl-gamma-lacton up
on demetalation. This synthetic sequence proceeds well for alkynylaldehydes
and the MOM derivative of tungsten-eta(1)-(3R,4S)-pent-1-yne-3,4-diol. The
resulting butyrolactone products are transformed into natural trisubstitut
ed butyrolactones including (+)-blastmycinone, (+)-blastmycinolactol, (+)an
timycinone, NFX-2, and (+)-isodihydromahubanolide A. By using the same appr
oach based on (R)-ethyl lactate, the natural (-)-litsenolide C-1 can be pre
pared in a few steps.