顺,顺,顺-3,6,9-二十碳三烯及顺,顺,顺-3,6-9-二十一碳三烯的合成

由于昆虫信息素研究的需要,我们曾于1979年合成了顺、顺、顺-3,6,9-二十碳三烯(1)和顺、顺、顺-3,6,9-二十一碳三烯(2),最近Conner等报道,1和2为鳞翅目昆虫信息素组分,并发表了以亚麻油酸及亚麻油醇为原料的合成路线。本文报道我们的合成路线,以丙炔醇为原料,经2-戊炔醇-[1](3),1-溴-2-戊炔     

Enantioselective syntheses of diquinane and (cis,anti, cis)-linear triquinanes

The enantioselective syntheses of diquinane and cis, anti, cis-linear triquinanes, starting from the readily available (S)-campholenaldehyde, employing an intramolecular rhodium carbenoid CH insertion reaction, are described.     

Technology for the identification of unusual cis, cis octadecadienoic fatty acids.

In this article methods are presented for the separation and identification of unusual cis, cis dienoic and polygnoic long chain fatty acids. Special emphasis has been laid on the identification of cis, cis octadecadienoic acids. The steps followed are: after transesterification the fatty acid methyl esters are separated by preparative gas chromatography according to chain length followed by argentation chromatography on thin-layer plates. After hydroxylation of the double bonds with osmium tetroxide the polyhydroxy compounds are derivatized to the per-O-trimethylsilyl-ethers. Separation and identification of individual compounds are achieved by combined gas chromatography-mass spectrometry using SCOT columns and low ionization energy.     

Benzoannelated cis,cis,cis,trans-[5.5.5.6]fenestranes: syntheses, base lability, and flattened molecular structure of strained epimers of the all-cis series

Tribenzofenestranes possessing the strained cis,cis,cis,trans-[5.5.5.6]-fenestrane skeleton have been synthesized from cis-2,6-diphenylspiro[cyclohexane-1,2'-indane]-1',3'-diols by two-fold cyclodehydration, in striking analogy to the strategy used previously to construct the stereoisomeric all-cis-tribenzo[5.5.5.6]fenestranes from the corresponding trans-diphenylspirodiols. In this manner, both of the parent hydrocarbons, all-cis-tribenzo[5.5.5.6]fenestrane 3 and cis,cis,cis,trans-tribenzo[5.5.5.6]fenestrane 4, have been made accessible from the spirodiketones 5 and 6, respectively. The C6-functionalized derivatives of 4-cis,cis,cis,trans-fenestranol 9 and cis,cis,cis,trans-fenestranone 12-were prepared through cis-diphenylspirotriol 8 and cis-diphenyldispiroacetaldiol 11, by using the same strategy. The cis,cis,cis,trans-[5.5.5.6]fenestrane framework readily epimerizes to the more stable all-cis isomers under basic conditions, but is stable under neutral or acidic conditions. For example, cis,cis,cis,trans-fenestranone 12 yielded all-cis fenestrane 3 under Wolff-Kishner conditions, but cis,cis,cis,trans-isomer 4 under Clemmensen conditions. Epimerization was also circumvented by radical-induced desulfurization of fenestrane dithiolane 15 with nBu3SnH/AIBN, producing 4 in excellent yields. A single-crystal X-ray structure analysis of 4 revealed that, in accordance with force field and semi-empirical MO calculations, the extra strain of the benzoannelated cis,cis,cis,trans-[5.5.5.6]fenestratriene framework [Estrain(4)-Estrain(3)=46 kJmol(-1)] is due both to the almost perfect boat conformation of the six-membered ring and to considerable bond angle widening at the central, non-bridged C4b-C15d-C11b unit (121 degrees). H/D exchange experiments with the cis,cis,cis,trans hydrocarbon 4 under basic conditions demonstrated that the strain-induced epimerization to 3 occurs through direct deprotonation of the "epimeric" benzylic bridgehead C7a-H bond, which was found to be more acidic than the two C-H bonds at the benzhydrylic bridgeheads.