作者:Xuan B. Nguyen、Yuji Nakano、Nisharnthi M. Duggan、Lydia Scott、Martin Breugst、David W. Lupton
DOI:10.1002/anie.201905475
日期:2019.8.12
Direct polarity inversion of conjugate acceptors provides a valuable entry to homoenolates. N‐heterocyclic carbene (NHC) catalyzed reactions, in which β‐unsubstituted conjugate acceptors undergo homoenolate formation and C−C bond formation twice, have been developed. Specifically, the all‐carbon (5+1) annulations give a range of mono‐ and bicyclic cyclohexanones (31 examples). In the first family of
route to clavilactone B, a naturally occurring inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, is disclosed. The route features a sequential samarium-mediated radical cyclization–fragmentation of an indanone derivative, which provides rapid access to a 10-membered carbocyclic motif fused to an aromatic ring.
Asymmetric Catalysis. Asymmetric Catalytic Intramolecular Hydroacylation of 4-Pentenals Using Chiral Rhodium Diphosphine Catalysts
作者:Richard W. Barnhart、Xianqi Wang、Pedro Noheda、Steven H. Bergens、John Whelan、B. Bosnich
DOI:10.1021/ja00084a025
日期:1994.3
Catalysts of the type [Rh(chiral diphosphine)] + convert 4-substituted 4-pentenals into the corresponding 3-substituted cyclopentanones with generally high turnover numbers and frequencies at 25 o C. The enantioselectivities of various substituted 4-pentenals with two chiral diphosphines have been explored. It was found that with the binap catalyst, almost complete enantioselectivity is observed for
[Rh(手性二膦)] + 类型的催化剂在 25 o C 下将 4-取代的 4-戊烯醛转化为相应的 3-取代的环戊酮,其转换数和频率通常很高。 具有两个手性二膦的各种取代的 4-戊烯醛的对映选择性已被探索。发现使用 binap 催化剂,对于带有 4-取代叔取代基的 4-戊烯醛底物和酯基,观察到几乎完全的对映选择性。酮取代基具有非常高的对映选择性
Enantioselective N‐Heterocyclic Carbene Catalyzed Cyclopentene Synthesis via the β‐Azolium Ylide
作者:Lydia Scott、Yuji Nakano、Changhe Zhang、David W. Lupton
DOI:10.1002/anie.201804271
日期:2018.8.6
cycloisomerization of electron‐poor 1,5‐dienes via the β‐azolium ylide to give enantioenriched cyclopentenes. The reaction is mediated by a chiral N‐heterocycliccarbene (NHC) catalyst, exploits readily available substrates, has good generality (17 examples), and displays excellent enantioselectivity (mostly >94:6). Studies demonstrating the viability of a related dynamic kinetic resolution are reported, as
Asymmetric catalysis. Asymmetric catalytic intramolocular hydrosilation and hydroacylation
作者:Richard W. Barnhart、Xianqi Wang、Pedro Noheda、Steven H. Bergens、John Whelan、B. Bosnich
DOI:10.1016/s0040-4020(01)89370-4
日期:1994.4
type [Rh(chiral Diphosphine)]+ efficiently catalyse the intramolecular hydrosilation of silylethers derived fromallylicalcohol. The products can be converted to chiral 1,3-dols. High enantiomeric excesses (ee's) are observed for substrates bearing an aryl group at the olefin terminus. These same catalyst produce chiral cyclopentanones from 4-substitued 4-pentenals. Tertiary acyl and ester substituents