ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Pyrylium Compounds. 34. 2-Acetonyl-2H-thiopyrans from 2,4,6-Triarylthiopyrylium Salts2,4,6-Triarylthiopyrylium salts 4 react with acetone in the presence of amine salts of weak acids (e.g. piperidine acetate) to give the hithero unknown 2-acetonyl-2-H-thiopyrans 5, the structure of which was established by spectroscopic methods. Depending on the nature of the amine salt used, the enamine 6 or the enol 7 of acetone may function as attacking nucleophile. Using the 2,4,6-triphenyl derivative 5a as model compound, some typical reactions of 2-acetonyl-2H-thiopyrans were studied. With 2,4-dinitrophenylhydrazine, semicarbazide and thiosemicarbazide, the carbonyl derivatives 10a-c are formed. Hydrogen peroxide in acetic acid affords the S,S-dioxide 11. Methanolic sodium methoxide or sodium hydroxide in aqueous ethanol give rise to a ring transformation yielding 1,3,5-triphenylbenzene (12) and 2,4,6-triphenylacetophenone (13). Under similar conditions, benzaldehyde reacts with 5a to give 2′, 4′, 6′-triphenylchalcone (14). Perchloric acid regenerates from 5a the initial thiopyrylium perchlorate 4a.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19863280417
