Reactions of Hexadehydro-Diels–Alder (HDDA)-Derived Benzynes with Thioamides: Synthesis of Dihydrobenzothiazino-Heterocyclics
作者:Vignesh Palani、Junhua Chen、Thomas R. Hoye
DOI:10.1021/acs.orglett.6b03199
日期:2016.12.16
Reaction of thioamides (e.g., II) with benzynes generated by the hexadehydro-Diels–Alder (HDDA) cycloisomerization (e.g., I) produces dihydrobenzothiazines (e.g., III). It is postulated that the reaction proceeds via benzothietene (cf. IV) and o-thiolatoaryliminium (cf. V) intermediates and that the latter undergoes intramolecular 1,3-hydrogen atom migration to produce the penultimate isomeric iminium
A general method for one-potsynthesis of thioamides without transition metals or external oxidants is developed through a three-component reaction involving chlorohydrocarbon, amide and elementalsulfur. Both alkyl and aryl thioamides could be obtained in moderate to excellent yields through this protocol. A high tolerance regarding various substituents on chlorohydrocarbon or amide was justified
Leveraging the Domino Skeletal Expansion of Thia-/Selenazolidinones via Nitrogen-Atom Transfer in Hexafluoroisopropanol: Room Temperature Access to Six-Membered S/Se,N-Heterocycles
作者:Vandana Jaiswal、Mangilal Godara、Dinabandhu Das、Vincent Gandon、Jaideep Saha
DOI:10.1021/acs.joc.1c02621
日期:2022.1.7
Herein, a highly regioselective domino skeletal-expansion process that transforms 2-aminothiazolidinone into six-membered S,N-heterocycle is developed with the aid of TMS-azide in hexafluoroisopropanol (HFIP) at ambient temperature. Functioning of the C2 tertiaryamine as latent reactive group on thiazolidinone moiety was the key to this development, which allowed relay substitution with azide and
α-Imino acids, prepared from α-ketoacids and primary amines, undergo facile decarboxylation to the corresponding imines on heating at ⩽,80°C in benzene or methylene chloride. Decarboxylation proceeds via a 1,2-ylide which can be trapped by sulphur to give the corresponding secondary thioamides in good yield. 1,2-Ylides from secondary amines and ∞-keto acids can be generated in situ and trapped with