α-Cubebene and β-cubebene. Synthetic proof of gross structure.

Tricyclic Sesquiterpenes from Marine Origin

“…(−)-Cubebol 79 and (−)-α-cubebene 84 were the subject of five asymmetric syntheses and one racemic route . The fisrt one , (Scheme ), which allowed confirmation of the ACs of the targets, started with the transformation of (−)- trans -caran-2-one 402 into spirolactone 403 in three steps and 16% yield.…”

“…(−)-Cubebol 79 and (−)-α-cubebene 84 were the subject of five asymmetric syntheses and one racemic route. 360 The fisrt one 88,361 Dehydration (with thionyl chloride in pyridine) of this species led to a mixture (7:2) of (−)-α-cubebene 84 and its epimer βcubebene 406 separated by GC without mention of the yield. This strategy, which had the merit of being the first reported access to these natural products, is relatively inefficient (OY = 0.8% for (−)-79) and, moreover, requires separation of products by preparative GC on many stages.…”

Cyclopropanation Strategies in Recent Total Syntheses

“…Except for two recent syntheses by Fürstner and Hannen and Fehr and co-workers, , all previous routes have highlighted an α-diazoketone to generate the internal cyclopropane (Scheme ). − However, these approaches suffer from moderate yields for the cyclopropanation reaction as well as low diastereoselectivities. In 2010, Hodgson et al .…”

“…165−170 However, these approaches suffer from moderate yields for the cyclopropanation reaction as well as low diastereoselectivities. In 2010, Hodgson et al 171 reported a novel synthesis of (−)-cubebol (168) starting from (−)-menthone (172), which was converted into Scheme 24. Total Syntheses of (+)-Propindilactone G and (+)-Schindilactone A a a Yang and co-workers.…”