Hydrolysis of 1,4,6-trioxaspiro[4.5]decanes to .delta.-lactones using 2,3-dichloro-5,6-dicyanobenzoquinone in aqueous acetone
摘要:
A selective hydrolysis of 1,4,6-trioxaspiro[4.5]decane orthoesters by 2,3-dichloro-5,6-dicyanoquinone (DDQ) in aqueous acetone in the presence of other acid-sensitive ketals is suggested to involve the formation of a charge-transfer complex followed by hydrolysis. A hydride-transfer mechanism for this oxidation was excluded.
A partial synthesis of (-)-shinjulactone H from (+)-quassin
摘要:
A partial synthesis of (-)-shinjulactone H (3) from (+)-quassin (1) required the selective manipulation of two similar O-methyldiosphenol groups. Protection of the delta-lactone in 1 as an ortho ester, selective reduction of the C-1 carbonyl group, hydrolysis of the resulting enol ether in the A ring, and catalytic hydrogenation of the O-methyldiosphenol in the C ring delivered an intermediate possessing an alpha-ketol group in the A ring and an alpha-methoxy ketone group in the C ring. Demethylation and concomitant alpha-ketol tautomerization in the A ring delivered (-)-shinjulactone H (3).