A. Gil Fortes

Cycloaddition of methyl 2-(2,6-dichorophenyl)-2H-azirine-3-carboxylate to electron rich 2-azadienes

Abstract tert -Butyldimethylsililoxy-2-aza-1,3-butadienes react with 2 H -azirine 3 leading to Diels–Alder cycloadducts in moderate yields. The reactions are endo - and regioselective with the azirine being added by its less hindered face. There is only one product in the case of 1b , 4b . There are two isomers ( 4 and 5 ) from 1a , 1c and 1d . A different result was obtained with the diene 1e . Diene 1e formed products 4e and 8 . Some of compounds 4 and 5 have been hydrolysed leading to functionalised aziridines 7 . Compound 8 gave aziridine 9 .

Optically active aziridine esters by nucleophilic addition of nitrogen heterocycles to a chiral 2H-azirine-2-carboxylic ester

Chiral enriched ethyl 3-methyl-2H-azirine-2-carboxylate acts as an efficient alkylating agent for a variety of five-membered aromatic nitrogen heterocycles.

Synthesis of 1,3,8,8a-tetrahydro-3,8-epoxyazirino[1,2-b]isoquinolines and their reactions with oxygen nucleophiles

Cycloadditions of 2H-azirines to isobenzofurans is described. The endo and exo products were obtained and were reacted with oxygen nucleophiles. Tetrahydroquinolines or benzofuranols were obtained, usually in excellent yields. Cycloaddition of the less electrophilic azirine (14) was performed at room temperature in the presence of ZnCl 2 . The cycloadduct was hydrolysed in the reaction conditions, but dehydration to give back the original cycloadduct was obtained in the presence of 4A molecular sieves. The structure assigned in the literature to the product of hydrolysis of the cycloadduct (10) was rectified.

Stereoselective cycloaddition of 1-glucosyl-1,3-butadienes with tert-butyl 2H-azirine-3-carboxylate, glyoxylates and imines

Glucosyl dienes 1 have been reacted with the achiral 2H-azirine 4 and with glyoxylates, forming fused structures of type 5 and disaccharide-like compounds 7 with good to excellent selectivity. Glucosyl dienes 1 participated as dienophiles in reactions with Schiff bases derived from anilines forming isoquinolines 10 and 11. The diastereoselectivity of this reaction is poor.

Diels-Alder Cycloaddition in the Synthesis of 1-Azafagomine, Analogs, and Derivatives as Glycosidase Inhibitors

This comprehensive review deals with the synthesis of 1-azafagomine, analogs, and derivatives having the Diels-Alder cycloaddition as the key step. Most of the compounds referred are racemic or have been resolved by lipase transesterification. There are two asymmetric cycloadditions leading to 1-azafagomine or to an analog. In one case both enantiomers of 1-azafagomine were prepared together with a pair of derivatives. The study comprises glycosidase inhibition studies of the target compounds to a set of glycosidic enzymes, and evidenced molecular features that enhance or diminish their activity as glycosidase inhibitors.