Photochemical rearrangements of quinone monoketals
作者:Michael C. Pirrung、David S. Nunn
DOI:10.1016/0040-4020(96)00207-4
日期:1996.4
provides, after hydrolysis, β-carboxy-substituted cyclopentenones. With a substituent at the β-position of the quinone monoketal, rearrangement selectivity is modestly in favor of the more substituted alkene product. With a substituent at the α-position of the quinone monoketal, rearrangement selectivity is strongly in favor of the less substituted alkene product. Possible mechanistic reasoning to explain
Broad-Spectrum Enantioselective Diels−Alder Catalysis by Chiral, Cationic Oxazaborolidines
作者:Do Hyun Ryu、Thomas W. Lee、E. J. Corey
DOI:10.1021/ja027468h
日期:2002.8.1
catalysts for Diels-Alder addition of cyclopentadiene to a wide variety of dienophiles. Adducts have been obtained in excellent yield and enantioselectivity from alpha,beta-unsaturated esters, lactones, and cyclic ketones. The absolute facial selectivity for each of these substrates follows a common pattern which differs from that observed with alpha,beta-enals. The different reaction channels can be
A new procedure for the synthesis of quinone monoketals derived from a variety of diols has been developed involving treatment of the readily available dimethyl ketals with diols and BF3.etherate in DME.
Catalytic Enantioselective Diels−Alder Reactions of 1,4-Quinone Monoketals
作者:Matthias Breuning、E. J. Corey
DOI:10.1021/ol015852y
日期:2001.5.1
Achiral 1,4-quinone monoketals function well as dienophiles in enantioselectiveDiels−Alderreactions catalyzed by a chiral Ti(IV) Lewis acid.
在由手性 Ti(IV) Lewis 酸催化的对映选择性 Diels-Alder 反应中,非手性 1,4-醌单缩酮的作用很好。
Total Synthesis of (±)- and (−)-Daphnillonin B
作者:Yun-Peng Zou、Zheng-Lin Lai、Meng-Wei Zhang、Jianzhao Peng、Shuai Ning、Chuang-Chuang Li
DOI:10.1021/jacs.3c03755
日期:2023.5.24
The firsttotalsynthesis of (±)- and (−)-daphnillonin B, a daphnicyclidin-type alkaloid with a new [7-6-5-7-5-5] A/B/C/D/E/F hexacyclic core, has been achieved. The [6-5-7] B/C/D ring system was efficiently and diastereoselectively constructed via a mild type I intramolecular [5+2] cycloaddition, followed by a Grubbs II catalyst-catalyzed radical cyclization. The [5-5] fused E/F ring system was synthesized
(±)- 和 (−)-daphnillonin B 的首次全合成,一种具有新 [7-6-5-7-5-5] A/B/C/D/E/F 六环的 daphnicyclidin 型生物碱核心,已经实现。[6-5-7] B/C/D 环系统是通过温和的 I 型分子内 [5+2] 环加成,然后是 Grubbs II 催化剂催化的自由基环化,高效且非对映选择性地构建的。[5-5] 稠合 E/F 环系统是通过非对映选择性分子内 Pauson-Khand 反应合成的。值得注意的是,具有综合挑战性的 [7-6-5-7-5-5] 六环核心通过独特的 Wagner–Meerwein 型重排从 [6-6-5-7-5-5] 六环框架中发现重新组装calyciphylline A 型Daphniphyllum生物碱。