Bp. Pradhan et al., NOVEL METHOD FOR REDUCTIVE CLEAVAGE OF TRITERPENOID LACTONES WITH LITHIUM IN ETHYLENEDIAMINE, Indian journal of chemistry. Sect. B: organic chemistry, including medical chemistry, 32(7), 1993, pp. 721-725
Sterically hindered gamma-lactones furnish mainly the saturated carbox
ylic acids whereas delta-lactones with less hindrance yield the diols
in higher percentage compared to the acids. Epsilon-Lactones,however,
furnish the diols exclusively. The reduction is drastic and effective
when other methods fail.