A novel dihydroxy nor-guaiane sesquiterpene: synthesis and crystal structure analysis

Abstract

A epoxidação (H 2 O 2 , NaOH) de uma cicloeptenona-acetonilada forneceu um sesquiterpeno norguaiano bis-hidroxilado, através de uma seqüência inesperada de reações. Análise espectroscópica deste produto permitiu propor uma estrutura incluindo os grupos substituintes, porém a determinação tridimensional completa foi realizada por uma análise de difração de raio-X.The epoxidation (H 2 O 2 , NaOH) of an acetonyl-cycloheptenone derived from (R)-(-)-carvone gives a dihydroxy-nor-guaiane sesquiterpene by way of an interesting sequence of reactions promoted by the basic reaction conditions. Although the major product could be identified spectroscopically with respect to functional groups, its complete three dimensional structure was determined by X-ray mono-crystal diffraction studies.

Chemical Composition of Essential Oils from the Leaves ofEndlicheria bracteolata

“…The occurrence of substances with this type of skeleton is not common in the Lauraceae family 15 . The occurrence of substances with this type of skeleton is not common in the Lauraceae family 15 .…”

Unequivocal structural assignments of three cycloheptenoid intermediates for guaiane sesquiterpenes: an experimental and theoretical approach

“…This has provoked studies on the synthesis of suitable seven‐membered ring intermediates, frequently by expansion of readily available cyclohexane starting materials . Our approach is to utilise para ‐menthane monoterpenes, because of their availability, price, enantiomeric purity and occurrence in both series, and diverse functionality …”

The enantioselective synthesis of (R)-(+)-6-isopropenyl-3-methyl-2-cycloheptenone

“…Our interest in their synthesis has led us to develop methods for the transformation of para-menthane monoterpenes into single isomer cycloheptenones, [2][3][4] and then by pent-annelation 5,6 into the required complete carbon skeleton. Scheme 1 outlines our synthetic strategy which involves two quite different routes for the ring expansion, by cyclopropanation and central sigma bond cleavage 2,3 or nucleophilic addition and rearrangement.…”

“…Scheme 1 outlines our synthetic strategy which involves two quite different routes for the ring expansion, by cyclopropanation and central sigma bond cleavage 2,3 or nucleophilic addition and rearrangement. 4 The intermediate cycloheptenone can then by pent-annelated by more classical ionic reactions (allylation, Wacker oxidation and intramolecular aldol reaction) 5 or by the ring closing metathesis 6 of a suitable neighboring allyl-vinyl derivative.…”