Head-space volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae, were analyzed by coupled CC-MS and chiral gas chromatography. 5-Ethyl-7-methyl-6,8-dioxabicyclo[3.2.1] (6) was found as a new naturally occurring isomer of brevicomin (1). In addition, several stereoisomers of 7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1] (11) and 1-(5-methyl-6,8-dioxabicyclo[3.2.1]octyl)ethanol (12) could be identified. Relative and absolute configurations of the compounds were determined by unambiguous syntheses, which are described. Copyright (C) 1996 Elsevier Science Ltd
The Effects of Ring Size and Substituents on the Rates of Acid-Catalysed Hydrolysis of Five- and Six-Membered Ring Cyclic Ketone Acetals
作者:Jonathan P. Knowles、Andrew Whiting
DOI:10.1002/ejoc.200700244
日期:2007.7
A series of sterically similar five- and six-membered ring cyclic diol-derived ketone acetals have been prepared and their rates of acid-catalysed hydrolysis examined. The rates of hydrolysis are substantially affected by acetal ring conformational stereoelectronic effects and resonance effects depending upon the substituents on the parent ketone; an A1 mechanism of hydrolysis explains the observed
Synthesis and Olfactory Properties of Seco-Analogues of Lilac Aldehydes
作者:Vladimír Dacho、Peter Szolcsányi
DOI:10.3390/molecules26237086
日期:——
Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designed, prepared, and evaluated a set of racemic seco-analogues of such natural products. The synthesis employs commercially available α-chloroketones as substrates that are transformed in four steps to target compounds. Their qualitativeolfactory analysis revealed that the opening of the tetrahydrofuran ring