Unexpected Rearrangement in the Heck Cyclization of Positional Isomers of Chiral 2,3-Disubstituted Perhydro-1,3-benzoxazines

Abstract

The intramolecular Heck cyclization on 2,3-disubstituted perhydro-1,3-benzoxazines, derived from (-)-8-amino menthol, easily proceeds at reflux of acetonitrile or DMF. The behavior of positional isomers was quite different. Reaction of 2-aryl-3-allyl perhydro-1,3-benzoxazines occurred as expected giving exclusively 6-exo cyclization products. On the contrary, regioisomeric 3-(iodobenzyl)-2-vinyl derivatives gave the normal cyclization compounds and rearranged 1,2-dihydroisoquinoline nucleus.

1,3-Aminoalcohols and Their Derivatives in Asymmetric Organic Synthesis

“…Aminoalcohol 45 has also been used as a chiral auxiliary for intramolecular Heck reactions . Precursors 306 , 307 , and 312 were prepared from 45 in the usual fashion.…”

“…Aminoalcohol 45 has also been used as a chiral auxiliary for intramolecular Heck reactions. 64 Precursors 306, 307, and 312 were prepared from 45 in the usual fashion. Reaction with catalytic Pd and PPh 3 in refluxing MeCN gave cyclization products 308-310 and 313-316 (Tables 34 and 35).…”

Stereoselective synthesis and application of bi- and trifunctional monoterpene-based compounds

“…32 Application of alicyclic 1,3-aminoalcohols in various pericyclic reactions has also been thoroughly investigated, their successful use in Diels-Alder reactions 33-36 , 1,3-dipolar cycloadditions 28,37 and also in intramolecular Alder-Ene reactions have been reported. 38 They also proved to be useful in palladium catalysed allylic alkylations [39][40][41] and in Heck-reactions 42 as catalysts and they also have a significant role in rhodium catalysed catalytic hydrogenation reactions. 43 The most investigated and frequent applicacation of alicyclic 1,3-aminoalcohols is stereoselective nucleophilic addition of organozinc reagents to various aldehydes and ketones.…”

“…As the interconversion between the oxazolidines and oxazines is fast, freshly prepared compounds were used in the catalytic reaction. The synthesized pinane-based N-protected diaminoalcohols (37-41), oxazolidinones (42)(43)(44)(45)(46)48) and tridentate diaminoalcohols (49,50,(56)(57)(58) were applied in the model reaction.…”