STEREOSTRUCTURE OF RENGYOL AND ISORENGYOL, PHENYLETHANOIDS OF FORSYTHIA SUSPENSA

Article abstract of DOI:10.1016/S0040-4020(01)86873-3

Determination of the stereostructure of rengyol (1), a novel nonaromatic phenylethanoid natural product isolated from Forsythia suspensa, by synthetic means has been described.The Reformatsky reaction of 4-acetoxycyclohexanone with ethyl bromoacetate afforded two isomeric acetoxy esters (5, 6) and the one (5) which has an equatorial acetoxyl group yielded on LAH reduction a triol identified as rengyol (1).The isomer (7), obtained similarly from the other isomeric acetoxy ester (6), has also been isolated from the natural source and is named isorengyol.Further, dehydratation of the esters (5, 6) and subsequent pyrolytic deacetoxylation afforded a 1,3-cyclohaxadiene derivative (12), which on photosensitized cis-dioxygenation, followed by reduction, yielded rengyol (1) establishing its stereostructure to have 1,4-cis-cyclohexanediol system.These results supported the previous conclusion based on the 1H and 13C NMR spectral data.