72856-35-0Relevant academic research and scientific papers
Highly diastereoselective cycloaddition reactions of variously substituted 1-thia- and 1-thia-3-aza-buta-1,3-dienes. Synthesis of enantiomerically pure 5,6-dihydro-4H-[1,3]thiazines and 3,4-dihydro-2H-thiopyrans
Harrison-Marchand, Anne,Collet, Sylvain,Guingant, André,Pradère, Jean-Paul,Toupet, Lo?c
, p. 1827 - 1839 (2007/10/03)
The cycloaddition of 2- or 2,3-substituted 1-thia- and 1-thia-3-aza-4- dimethylamino-buta-1,3-dienes with various dienophiles in the presence of a Lewis acid provides a rapid and diastereoselective access to the 3,4-dihydro-2H-thiopyran and 5,6-dihydro-4H-[1,3]thiazine backbones. The generally observed trans relationship between the two newly created strereogenic centres was demonstrated to be the expression of a thermodynamic control of the reaction. The use of chiral dienophile derived from chiral oxazolidin-2-ones allowed us to prepare enantiopure 5,6-dihydro-4H-[1,3] thiazines and 3,4-dihydro-2H-thiopyrans. In the asymmetric synthetic process the chiral auxiliary removal step was best accomplished in the presence of samarium triflate in methanol.
Des 6H-thiazines-1,3 aux cephemes par cyclocondensation
Pradere, J. P.,Roze, J. C.,Quiniou, H.,Danion-Bougot, R.,Danion, D.,Toupet, L.
, p. 597 - 602 (2007/10/02)
The synthesis of new thiazines is described.Their structural determination and their spectroscopic parameters are examined.The cyclocondensation of these thiazines with ketenes is studied along with the reversibility of the reaction as a function of the nature of the substituents on position 4 and (or) 5 of 6H-1,3-thiazines.
