Stereoselective synthesis of (−)-malyngolide, (+)-malyngolide and (+)-tanikolide using ring-closing metathesis
作者:Miguel Carda、Santiago Rodrı́guez、Encarnación Castillo、Alejandro Bellido、Santiago Dı́az-Oltra、J Alberto Marco
DOI:10.1016/s0040-4020(02)01594-6
日期:2003.2
The stereoselective syntheses of the naturally occurring δ-lactones (+)-tanikolide and (−)-malyngolide as well as of the unnatural (+)-enantiomer of the latter are described. Key steps in each of these syntheses were stereoselective additions of organometallic reagents to α-oxygenated ketones and olefin ring-closing metatheses.
Synthesis of chiral alkenyl epoxides: the sex pheromone of the elm spanworm Ennomus subsignaria (Hübner) (Lepidoptera: Geometridae)
作者:David I. MaGee、Peter J. Silk、Junping Wu、Peter D. Mayo、Krista Ryall
DOI:10.1016/j.tet.2011.05.015
日期:2011.7
The identification of the sex pheromone of the elm spanworm Ennomos subsignaria (Hubner), as the chiral alkenyl epoxide (6Z)-cis-9,10-epoxy-nonadecene has been accomplished. Both enantiomers of (6Z)-cis-9,10-epoxy-nonadecene have been synthesized via two routes. The key steps in the first route were to prepare both threo-epoxy tosylates and then to perform an alkylative rearrangement of these intermediates to obtain the target molecules. An alternative enantioenriched synthesis that took advantage of the Sharpless dihydroxylation reaction was developed so that a common starting material could be used to access both enantiomers. A field study and GC/EAD testing indicated that Z6-cis-9S,10R-epoxy-nonadecene was the sex pheromone of the elm spanworm E. subsignaria (Hubner). (C) 2011 Elsevier Ltd. All rights reserved.
ICHIMOTO, ITSUO;MACHIYA, KOZO;KIRIHATA, MITSUNORI;UEDA, HIROO, AGR. AND BIOL. CHEM., 54,(1990) N, C. 657-662
A convenient synthetic method for the marine antibiotic (−)-malyngolide and its stereoisomers was accomplished from a chiral α-alkoxyketone (4), which was readily available as a chiron. Chiral quaternary carbon synthons (5a) and (5b) as the key intermediates were constructed by the chelation controlled addition of Grignard reagent to 4.The diastereomeric mixture of 5a and 5b was readily transformed into a separable mixture of lactones (7a) and (7b), each of which could be easily separated by silica-gel column chromatography. (−)-Malyngolide and its three steroisomers were obtained in optically pure form without the need for optical resolution.