RESOLUTION OF STERICALLY OVERCROWDED ETHYLENES - A REMARKABLE CORRELATION BETWEEN BOND LENGTHS AND RACEMIZATION BARRIERS

TETRAHEDRON LETTERS

卷:33

Article

关键词: ALKENES;    OVERCROWDED;    RESOLUTION;    KINETICS;    CORRELATION;   

DOI  :  10.1016/S0040-4039(00)78887-3

来源: Elsevier

【 摘 要 】

The synthesis and resolution of 2-methyl-9H-thioxanthene-9-(9H-thioxanthen-9-ylidene) 1 and related structures 2-5, being the first examples of thermally stable optically active sterically overcrowded ethylenes, are reported. Substitution of the sulfur atom in the thioxanthene part of 1 with an X group (2, X = C(CH3)2; 3, NCH3; 4, O) results in a change in racemization barrier (1, 27.4 kcal.mol-1; 2, 25.1 kcal.mol-1; 3, 21.3 kcal.mol-1; 4, < 20 kcal.mol-1) depending upon the aryl-X bond lenghts.

【 授权许可】

Free