Synthesis of (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus, its racemate, (1R,4R)- and (1S,4S)-isomers
摘要:
(S)-Perillyl alcohol was converted to (R)-cryptone (91.5-93% ee) in six steps, which was then treated with methyllithium to give (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus. The racemic pheromone was also prepared by methylation of (+/-)-cryptone. Both (1R,4R)- and (1S,4S)-isomers (98% ee) of the pheromone were synthesized from the enantiomers of dihydrolimonene oxide. (c) 2006 Elsevier Ltd. All rights reserved.
The invention provides novel six and seven-carbon termini-differentiated polypropionate stereotetrads and stereopentads useful in syntheses of natural products. The invention also provides a novel alkylative sulfenylation-desulfonylation process that efficiently transforms enantiopure epoxyvinyl sulfones to syn and anti dienylsulfides in two operations.
Et<sub>3</sub>B-mediated two- and three-component coupling reactions via radical decarbonylation of α-alkoxyacyl tellurides: single-step construction of densely oxygenated carboskeletons
three-component coupling reactions of sugar derivatives, without the need for light or heat. Et3B/O2-mediated decarbonylation readily converted α-alkoxyacyl tellurides to α-alkoxy carbon radicals, which intermolecularly added to glyoxylic oxime ether or enones to provide the two-component adducts. Furthermore, the three-component adducts were produced by an intermolecular aldol reaction between the aldehyde
通过糖衍生物的基于自由基的二元和三元偶联反应,无需光或热,即可一步构建各种高氧碳骨架。Et 3 B/O 2介导的脱羰反应很容易将α-烷氧基酰基碲化物转化为α-烷氧基碳自由基,其分子间加成到乙醛肟醚或烯酮中以提供双组分加合物。此外,三组分加合物是通过醛和硼烯醇化物之间的分子间醛醇反应产生的,该反应是由 Et 3 B 捕获双组分自由基中间体产生的。这种强大的偶联方法是聚合合成多元醇天然产物。
Total syntheses of (+)-adunctins C and D: assignment of their absolute configurations
作者:Jian Xiao、Jun Zhao、Ya-Wen Wang、Gan Luo、Yu Peng
DOI:10.1039/d1ob02055b
日期:——
The first totalsynthesis of (+)-adunctin C (ent-1) and (+)-adunctin D (2), two monoterpene-substitued dihydrochalcones isolated from Piper aduncum (Piperaceae), was achieved. A regioselective oxidative [3 + 2] cycloaddition of acylphloroglucinol with (−)-β-phellandrene was developed to construct their unique spirobenzofuran skeleton. The absolute configurations of natural adunctins 1 and 2 were thus
(+)-adunctin C ( ent - 1 ) 和 (+)-adunctin D ( 2 ) 是从Piper aduncum (Piperaceae) 中分离出来的两种单萜取代的二氢查尔酮,首次实现了全合成。开发了酰基间苯三酚与 (-)-β-水芹烯的区域选择性氧化 [3 + 2] 环加成,以构建其独特的螺苯并呋喃骨架。因此,通过这些努力分配了天然 adunctins 1和2的绝对构型。
Trimethylchlorosilane induced ring opening of 2-alkyloxazolidines to enamine derivatives
2-Alkyloxazolidines (5) were ring-opened by trimethylchlorosilane with N,N-diisopropylamine to give N-[2-(trimethylsilyloxy)alkyll-enamines (6). A MgCl2 promoted Michael reaction of chiral enamines thus prepared was achieved with asymmetric induction.
Total synthesis of eudesmane terpenes: cyclase phase
作者:Ke Chen、Yoshihiro Ishihara、María Morón Galán、Phil S. Baran
DOI:10.1016/j.tet.2010.02.088
日期:2010.6
of the lowest oxidized members of the eudesmane family of natural products, is presented. The final synthetic sequence illustrates a nine-step, gram-scale, enantioselective route to this bicyclic terpene with excellent stereocontrol and in 21% overall yield.