Hetero-Diels−Alder Reactions of Homochiral 1,2-Diaza-1,3-butadienes with Diethyl Azodicarboxylate under Microwave Irradiation. Theoretical Rationale of the Stereochemical Outcome

Amphipathic 1,3-oxazolidines from N-alkyl glucamines and benzaldehydes: stereochemical and mechanistic studies

Chiral N,O-heterocycles appended to a non-reducing carbohydrate chain, which are valuable synthons, reveal further stereodynamic implications.

Molecular diversity of TEMPO-mediated cycloaddition of ketohydrazones and 3-phenacylideneoxindoles

This reaction selectively proceeded via aza-Diels–Alder reaction, [3+2] cycloaddition and ring-opening of oxindole to give diverse spirooxindoles and polysubstituted pyrazoles.

Direct access to non-aromatic 1,2,3,6-tetrahydro-1,2,3,4-tetrazines via [4 + 2] cycloaddition of α-halogeno hydrazones with azodicarboxylic acid derivatives

Construction of non-aromatic 1,2,3,6-tetrahydro-1,2,3,4-tetrazines through [4 + 2] cycloaddition of α-halogeno hydrazones with azodicarboxylic acid derivatives.

Microwave-assisted Diels–Alder reaction of 1,3,3-trimethyl-2-vinyl-1-cyclohexene with chromones — An expeditious approach to analogues of the puupehenone group of marine diterpenoids and kampanols

A rapid assembly of the tetracyclic core of marine diterpenoids related to puupehenone and kampanols by a Diels–Alder reaction of 1,3,3-trimethyl-2-vinyl-1-cyclohexene with chromones under microwave irradiation with or without TiCl4 is described.

Cyclic vinyl p-tolyl sulfilimines as chiral dienophiles: theoretical study on the stereoselectivity, Lewis acid catalysis, and solvent effects in their Diels-Alder reactions

The theoretical study reported in the present work deals with chiral cyclic vinyl sulfilimines and their reactivity as dienophiles in [4 + 2] cycloaddition reactions, using B3LYP/6-31G(d)//AM1 and B3LYP/6-31G(d)//B3LYP/6-31G(d) model chemistries. Consideration of Lewis acid catalysis, illustrated by BF(3), decreases the activation energies of the cycloaddition process while the charge transfer from the diene to the sulfilimine is augmented. The [4 + 2] cycloaddition reactions of sulfilimines with both furan and cyclopentadiene occur in the gas phase with endo stereoselectivity, which is more pronounced with the latter diene. Endo-exo energy differences in the gas phase with the B3LYP/6-31+G(d)//B3LYP/6-31+G(d), B3LYP/6-31G(d)//B3LYP/6-31G(d), and B3LYP/6-31G(d)//AM1 model chemistries are almost the same. Solvent effects are responsible for the inversion of the stereoselectivity in the reactions of sulfilimines with furan because of the great difference in the dipole moments in endo and exo approaches.

Microwave-assisted [6+4]-cycloaddition of fulvenes and alpha-pyrones to azulene-indoles: facile syntheses of novel antineoplastic agents

A microwave-enhanced [6+4]-cycloaddition reaction between 6-aminofulvene and pyrones followed by CO(2) extrusion provides azulene-indoles which display interesting antineoplastic activity.