THE GLYCOSIDIC PRECURSOR OF (Z)-5-ETHYLIDENE-2(5H)-FURANONE IN HALOCARPUS-BIFORMIS JUVENILE FOLIAGE

A new glycosidic lactone, (5R,6R)-5-(1-hydroxyethyl)-2(5H)-furanone be ta-D-glucopyranoside, has been identified as the principal precursor o f (Z)-5-ethylidene-2(5H)-furanone in juvenile foliage of the New Zeala nd tree Halocarpus biformis. Three related lactone glycosides were iso lated in smaller amounts, together with the known phenolic glycosides pyroside, arbutin and picein. The principal lactone glycoside underwen t facile elimination of glucose, in neutral or basic conditions, to yi eld (2)-5-ethylidene-2(5H)-furanone and its E-isomer. This lactone gly coside was also detected in foliage of H. bidwillii and H. kirkii.