作者:Sunggak Kim、Chae Jo Lim、Changsik Song、Won-jin Chung
DOI:10.1021/ja028396x
日期:2002.12.1
organic reactions, radical-mediated alkylations of carboxylic acid derivatives have not been well studied. The first successful radical alkylation of carboxylic imides is achieved by the addition of an alkyl radical to a ketene O,N-acetal and the subsequent cleavage of N-O bond. It is noteworthy that alkyl halides activated with an electron-withdrawing group undergo alkylations undertin-free conditions
尽管烷基化是最重要和最基本的有机反应之一,但羧酸衍生物的自由基介导的烷基化尚未得到很好的研究。羧酸酰亚胺的第一次成功的自由基烷基化是通过将烷基添加到烯酮 O,N-缩醛上并随后裂解 NO 键来实现的。值得注意的是,由于 1,2-苯基从甲硅烷基转移到氧,被吸电子基团活化的卤代烷在无锡条件下发生烷基化。
Enantiomerically pure cycloalkenylacetic acid derivatives via Pd-catalyzed asymmetric allylic alkylation and subsequent enantiomeric enrichment via iodolactones
作者:Peter Sennhenn、Bert Gabler、Günter Helmchen
DOI:10.1016/s0040-4039(00)78445-0
日期:1994.11
with stereogenic phosphorus were used as catalysts for alkylation of cycloalkenyl acetates which gave products with up to 85% ee. Excellent reactivity allowed reactions with as little as 0.02 mol% of Pd. Five- and six-membered ring synthons of interest for syntheses of biologically active compounds with > 99% ee were obtained via recrystallization of iodolactones.
Enantioselective Iodolactonization of Disubstituted Olefinic Acids Using a Bifunctional Catalyst
作者:Chao Fang、Daniel H. Paull、J. Caleb Hethcox、Christopher R. Shugrue、Stephen F. Martin
DOI:10.1021/ol3030555
日期:2012.12.21
The enantioselectiveiodolactonizations of a series of diversely substituted olefinic carboxylic acids are promoted by a BINOL-derived, bifunctional catalyst. Reactions involving 5-alkyl- and 5-aryl-4(Z)-pentenoic acids and 6-alkyl- and 6-aryl-5(Z)-hexenoic acids provide the corresponding γ- and δ-lactones having stereogenic C–I bonds in excellent yields and >97:3 er. Significantly, this represents
BINOL 衍生的双功能催化剂促进了一系列不同取代的烯烃羧酸的对映选择性碘内酯化。涉及 5-烷基-和 5-芳基-4( Z )-戊烯酸和 6-烷基-和 6-芳基-5( Z )-己烯酸的反应提供相应的具有立体异构 C-I 键的 γ-和 δ-内酯以优异的产量和 >97:3 er。值得注意的是,这代表了第一种以高对映选择性促进溴和碘内酯化的有机催化剂。还证明了该催化剂诱导外消旋不饱和酸的动力学拆分的潜力。
Total Synthesis of (+)-Sieboldine A
作者:Stephen M. Canham、David J. France、Larry E. Overman
DOI:10.1021/ja103666n
日期:2010.6.16
The first totalsynthesis of (+)-sieboldine A was completed in 20 steps from readily available (3aS,6aR)-3,3a,4,6a-tetrahydro-2H-cyclopenta[b]furan-2-one (5). Key steps are as follows: (a) a pinacol-terminated 1,6-enyne cyclization reaction to form the cis-hydrindanone core (11 --> 12), (b) formation of the spiro tetrahydrofuran ring by stereoselective DMDO oxidation of tricyclic dihydropyran intermediate
A route comprising (i) a cycloaddition reaction of citraconic anhydride with the Winterfeldt auxiliary, (ii) hydride reduction of the cycloadduct, (iii) a (formal) ether formation, and (iv) a cycloreversion reaction allows efficient stereocontrol at C-2' in the synthesis of strigol and its structural analogues. (C) 1998 Elsevier Science Ltd. All rights reserved.