Cross-Dehydrogenative Coupling between Enamino Esters and Ketones: Synthesis of Tetrasubstituted Pyrroles
摘要:
Tetrasubstituted pyrroles have been synthesized via the cross-dehydrogenative coupling between enamino esters and acetone. Silver carbonate proved to be an effective oxidant, and no transition metal catalyst is necessary.
Oxidative Coupling of Enamines and Disulfides<i>via</i>Tetrabutylammonium Iodide/<i>tert-</i>Butyl Hydroperoxide-Mediated Intermolecular Oxidative C(<i>sp</i><sup><i>2</i></sup>)S Bond Formation Under Transition Metal-Free Conditions
作者:Jiyun Sun、Daisy Zhang-Negrerie、Yunfei Du
DOI:10.1002/adsc.201501099
日期:2016.6.30
compounds with disulfides in the presence of tert‐butyl hydroperoxide and a catalytic amount of tetrabutylammonium iodide conveniently afforded a variety of α‐thioenamine compounds through the intermolecular oxidative C(sp2)S coupling. Incorporating both of the sulfide moieties in the disulfides into the final products under oxidative conditions, this novel approach exhibits the feature of atom efficiency
Novel metal-free, readily available chiral catalytic systems for the enantioselective reduction of keto imines are reported. Different β-imino esters were reduced by trichlorosilane in the presence of 10 mol% of a chiral Lewis base easily obtained in one step only from prolinol, in high yields and in up to 85% enantioselectivity; imines bearing an inexpensive and removable chiral auxiliary, were reduced with complete control of the absolute stereochemistry. The methodology was successfully extended to the stereoselective synthesis of α-amino esters.
novel chiral Lewisbase catalysts were synthesized from L-serine and applied in the hydrosilylation of β-enamino esters, in which the optimal one promoted the reactions to afford a wide variety of β-amino esters in good yields with good enantioselectivities. It is noteworthy that several cyclic substrates were hydrosilylated under the optimal conditions to give the cyclic β-amino esters with high yields
Synthesis of Polysubstituted Pyrroles via PhI(OAc)2-Mediated Oxidative Coupling of Enamine Esters and Ketones
作者:Wei Yu、Jun-Yan Wang、Su-Ping Liu
DOI:10.1055/s-0029-1217743
日期:2009.9
Enamine esters or ketones could undergo homocoupling by the action of (diacetoxyiodo)benzene in the presence of BF 3 -OEt 2 , giving rise to pyrrole products. This reaction could be used to synthesize symmetric polysubstituted pyrroles. Some asymmetric polysubstituted pyrroles could also be prepared using this protocol.
2‐Diazo‐1‐phenyl‐2‐((trifluoromethyl)sulfonyl)ethan‐1‐one (diazo‐triflone) (2) is not only a building block but also a reagent. In this study, diazo‐triflone, which was originally used for the synthesis of β‐lactam triflones as a trifluoromethanesulfonyl (SO2CF3) building block under catalyst‐free thermal conditions, is redisclosed as an effective electrophilic trifluoromethylthiolation reagent under copper catalysis