ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Thioacetic acid and dithioacetic acid react with alkynederivatives of the type (CH3)2N—C≡C—CO—R (1) in the same way as other carboxylic acids: The addition to dimethylaminopropinal (1a) at low temperatures yields, after rearrangement of the very instable primary adducts, Z-3-acetoxy-N,N-dimethyl-thioacrylamide (Z-16) and Z-3-thioacetoxy-N,N-dimethylthioacrylamide (Z-17) respectively. The structure of the two compounds can be proved by spectroscopic evidence of 16 and 18, the latter being formed by elimination of thioketene from 17. According to the distribution of S-atoms in 16 and 17, two reaction pathways including 4-membered rings can be ruled out. Thus the rearrangement of 3-acyloxy-N,N-dimethyl-acrylamides most probably proceeds by a mechanism including a dipolar six-membered intermediate.This mechanism cannot be valid for the rearrangement of the adducts 2 of hydrohalogen acids, alcohols and amines to the alkyne-derivatives 1. The acid-catalysed reaction of 3-chloro-3-dimethylamino-propenal (2, X=Cl), labelled at position 1 with 13C, yields 3-chloro-N,N-dimethyl-acrylamide (3, X=Cl), containing the label exclusively at position 3. This result supports a mechanism including an immonium-oxetene 21 (X=Cl) as intermediate. - The experiments are in accord with kinetic investigations.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19730560726
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