Conjugateaddition to 1,4-dicarbonylbut-2-enes will generate an α-stereogenic center with respect to one of the carbonyl groups, which informally, can be considered as an inversion of normal reactivity patterns or umpolung protocol. In this paper, the addition of tert-butyl mercaptan to 1,4-dicarbonylbut-2-enes including (E)-4-oxo-4-arylbutenamides and (E)-4-oxo-4-arylbutenones has been developed,
A Novel Aromatic Electrophilic Substitution: Acylation of Aromatics with Cyclic Isoimidium Salts to Yield<i>N,N</i>-Disubstituted β-Aroylcarboxamides
作者:Alexandru R. Balaban、Theodor-Silviu Balaban、Gerhard V. Boyd
DOI:10.1055/s-1987-28012
日期:——
Cyclic isoimidium perchlorates derived from N,N-diethylphthalamic acid and the monomorpholides of succinic and maleic acid react with benezene, toluene or anisole in the presence of aluminium chloride to give the corresponding ß-aroylcarboxamides in moderate yields.
The strength of the weak: An L‐tert‐leucine‐derived amine–thioureacatalyst (see scheme, green box) promotes the asymmetric vinylogous conjugate addition reaction between γ‐aryl‐ and alkyl‐substituted butenolides with the butenamides and enoates shown. Computational studies show the preference for the observed stereochemistry is a result of favourable weak non‐bonding interactions, which stabilize
Synthesis of α-Stereogenic Amides and Ketones by Enantioselective Conjugate Addition of 1,4-Dicarbonyl But-2-enes
作者:Zhiyong Jiang、Yuanyong Yang、Yuanhang Pan、Yujun Zhao、Hongjun Liu、Choon-Hong Tan
DOI:10.1002/chem.200802601
日期:2009.5.4
Constructing α‐stereogenic amides and ketones: The highly regioselective and enantioselectiveconjugateaddition of 1,3‐dicarbonyl compounds to 1,4‐dicarbonyl but‐2‐enes has been developed with the chiral bicyclic guanidine as catalyst (ee values up to 97 %; see scheme).
Pd-Catalyzed Enantiodivergent and Regiospecific<i>phospha</i>-Michael Addition of Diphenylphosphine to 4-<i>oxo</i>-Enamides: Efficient Access to Chiral Phosphinocarboxamides and Their Analogues
作者:Renta Jonathan Chew、Xi-Rui Li、Yongxin Li、Sumod A. Pullarkat、Pak-Hing Leung
DOI:10.1002/chem.201406298
日期:2015.3.16
The palladacycle‐catalyzed asymmetric PH addition of 4‐oxo‐enamides has been developed, which provides efficientaccess to phosphinocarboxamides and their analogues. Solvent‐mediated reversal of stereoselectivity (ee from +96 % to −92 %) was observed, and the underlying mechanism that allows facile access to both enantiomers of the product by judicious choice of solvents is revealed.