Diastereoselective synthesis of trans-trifluoromethyl-β-lactams and α-alkyl-β-trifluoromethyl-β-amino esters
摘要:
The diastereoselective synthesis of beta-lactams was examined from N-tosyl-1-chloro-2,2,2-trifluoroethylamine 3 and various nonactivated aliphatic acid chlorides in the presence of a Bronsted base. The mild reaction conditions allowed to get trifluoromethyl-beta-lactams in good yields with high trans-diastereo selectivity. In addition, we also demonstrated that ring-opening of beta-lactams easily provided alpha-alkyl-beta-trifluoromethyl-beta-amino esters. (C) 2011 Elsevier Ltd. All rights reserved.
One-Pot Three-Component Synthesis of Vicinal Diamines via In Situ Aminal Formation and Carboamination
作者:Ugo Orcel、Jerome Waser
DOI:10.1002/anie.201607318
日期:2016.10.4
A synthesis of vicinal diamines via in situ aminalformation and carboamination of allyl amines is reported. Employing highly electron‐poor trifluoromethyl aldimines in their stable hemiaminal form was key to enable both a fast and complete aminalformation as well as the palladium‐catalyzed carboamination step. The conditions developed allow the introduction of a wide variety of alkynyl, vinyl, aryl
N-Tosyltrifluoroacetaldehyde imine (4) reacted with terminal olefins by only heating together to give the ene reactin products. This means the imine is much more reactive than trifluoroacetaldehyde (2) itself as an enophile. However, 4 was very sensitive to moisture and the yields were low even if it was used without isolation. Further, it did not react with non-terminal olefins. In the course on study of the mechanism of this reaction, we found that N-(2, 2, 2-trifluoro-1-ethoxyethyl)tosylamide (12), obtained by the reaction of trifluoroacetaldehyde ethyl hemiacetal (1) with tosylamide (3) in the presence of titanium(IV) chloride followed by addition of ethanol, reacted in the presence of sodium hydride and titanium(IV) chloride to give the same products from the ene reaction of 4 in much better yields. Interestingly, this reaction proceeded with non-terminal olefins.