188644-86-2Relevant academic research and scientific papers
Diastereoselective intramolecular Diels-Alder reaction of the furan diene. A facile access to enantiopure epoxy tetrahydroisoindolines
Andres, Celia,Maestro, Gregorio,Nieto, Javier,Pedrosa, Rafael,Garcia-Granda, Santiago,Perez-Carreno, Enrique
, p. 1463 - 1466 (1997)
2-(2'-Furfuryl)-N-acryloyl tetrahydro-1,3-benzoxazine 2a participates in diastereoselective intramolecular Diels-Alder reaction in very mild conditions leading to two diastereoisomeric exo-adducts with good diastereoselectivity. Chromatographic separation of both adduts, and further elimination of the menthol appendage allows to prepare enantiopure iso-indoline derivatives in excellent chemical yields.
A Short Diastereoselective Synthesis of Enantiopure Highly Substituted Tetrahydroepoxyisoindolines
Pedrosa, Rafael,Andres, Celia,Nieto, Javier
, p. 831 - 839 (2007/10/03)
Diastereoselective intramolecular Diels-Alder reaction on 3-allyl-2-furyl- or 3-furfuryl-2-vinyl-substituted chiral perhydro-1,3-benzoxazines derived from (-)-aminomenthol is described. The [4 + 2] cycloaddition is highly stereo- and regioselective leading to the thermodynamic adducts as major products. Reduction of the N,O-acetal, followed by elimination of the menthol appendage, allows both enantiomers of disubstituted epoxy tetrahydroisoindolines to be prepared. Nucleophilic ring opening of the N,O-moiety in the adducts by magnesium or aluminum derivatives, followed by elimination of the menthol, leads to the synthesis of enantiopure regioisomeric trisubstituted epoxy tetrahydroisoindolines with up to five stereocenters.
Thermal and Lewis acid catalyzed diastereoselective intramolecular Diels-Alder reaction on α,β-unsaturated amides derived from (-)-8- aminomenthol
Andres, Celia,Garcia-Valverde, Maria,Nieto, Javier,Pedrosa, Rafael
, p. 5230 - 5236 (2007/10/03)
Stereochemical aspects of the intramolecular Diels-Alder reaction on perhydro-1,3-benzoxazines derived from (-)-8-aminomenthol bearing α,β- unsaturated amides and the dienic component attached at C-2 are described. The thermal cyclization of 2-(2'-furyl) derivatives 2, 6, and 7 exclusively afforded mixtures of exo adducts. The product selectivity was highly dependent on the solvent of the reaction. In CH2Cl2, the kinetic products 3, 8, and 9 always predominated, whereas in hexane or toluene, less polar solvents, the thermodynamic adducts 4, 10, and 11 were formed as major diastereoisomers. In cyclizations catalyzed with equimolar or 2-fold excess of Lewis acid, the kinetic stereiosomers were predominant. Some Lewis acids catalyzed the reaction, but diethylaluminum chloride was the most effective. The cyclization on the perhydro-1,3-benzoxazine 13, bearing an open dienic component, was much less stereoselective, and a mixture of two exo and two endo possible stereoisomers were formed. Elimination of the menthol appendage in two steps by reductive ring opening of the N,O-acetal moiety and oxidation-elimination yielded enantiomerically pure tetrahydroisoindoline derivatives.
