Zerumbone (1) was isolated from fresh rhizomes of Zingiber zerumbet Smith in yields of 0.3-0.4% by simple steam distillation and recrystallization. 1 accepted 2 equiv of hydrogen cyanide at the C6 and C9 double bonds of the cross-conjugated dienone system to give a mixture of diastereomers 3a-d. In the presence of potassium cyanide, the dominant isomer 3a was isomerized to a mixture of 3a-d. Under controlled conditions, 1 added one mole of methanol regio- and stereoselectively at the C6 double bond to give adduct 4a. With potassium cyanide, 4a was transformed to the mixture of 3a-d. 1 took up one mole of bromine at C6 double bond to give a diastereomeric mixture of adducts 5a and 5b. Treatment of 5a with potassium cyanide gave a mixture of cyclopropanecarboxylic acid 6a and 6b. This unique ring-contracting cyclopropane formation is pictured as a sequential Favorskii type reaction. alpha-Cyclodextrin improved the selectivity and yields of the reactions conducted in an aqueous medium.
Benzylacetone is released by heated agarwood, when inhaled it has a potent effect on reducing the locomotor activity of mice. This study investigated the relationships between the sedative activities of benzylacetone and its derivatives as well as the chemical structures of these compounds by comparing their activities in mice treated with a series of compounds. It was demonstrated that benzylacetone-like compounds had sedative activities and their intensities varied depending on the functional group in the carbon chain, the substituent in the benzene ring, and their combinations. A quantitative structure-activity relationship study was carried out using a series of 17 benzylacetone derivatives to determine the structural features with significant for the sedative activity.
The organocatalyzed asymmetric synthesis of efavirenz was achieved in five steps from a commercially available substrate through the operationally simple, enantioselective trifluoromethylation of an alkynyl ketone by using the Rup-
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