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Relative Reactivities of Carbonyl and Thiocarbonyl Groups toward Dimethoxycarbene: Two New Dimethoxythiiranes
Author(s) -
Dawid Małgorzata,
Mloston Grzegorz,
Warkentin John
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020503)8:9<2184::aid-chem2184>3.0.co;2-2
Subject(s) - chemistry , ring (chemistry) , carbonyl group , medicinal chemistry , carbene , thermal decomposition , group (periodic table) , double bond , polymer chemistry , organic chemistry , catalysis
Reaction of dimethoxycarbene (DMC), generated by thermolysis of a 2,5‐dihydro‐1,3,4‐oxadiazole, with 2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone afforded primarily 2,2‐dimethoxy‐3,3,5,5‐tetramethyl‐4‐thioxocyclopentanone from ring expansion by overall insertion into the C−CO bond. 4,4‐Dimethoxy‐2,2,5,5‐tetramethyl‐3‐thioxocyclopentanone, from overall insertion into a C−CS bond, was a minor product. Thus the carbene had reacted preferentially at the carbonyl group, rather than the thiocarbonyl group of the four‐membered ring. However, the minor product reacted with DMC at the thiocarbonyl group to afford a dimethoxythiirane. A product from a corresponding reaction at the carbonyl group could not be found. A rationale for the apparent reversal of relative reactivities of the carbonyl and thiocarbonyl groups is offered, with supporting evidence.