197239-74-0Relevant academic research and scientific papers
A Convenient Synthesis of 3,3-Dichloroazetidines, a New Class of Azetidines
Aelterman, Wim,De Kimpe, Norbert,Declercq, Jean-Paul
, p. 6 - 11 (1998)
A short synthesis of appropriately substituted 3,3-dichloroazetidines, a virtually unknown class of azetidines, is described. The reaction of 3,3-dichloro-1-azaallylic carbanions, generated from N-(1-aryl-2,2-dichloroethylidene)amines, with aromatic aldehydes produced α,α-dichloro-α-hydroxy imines that, upon treatment with mesyl chloride, were converted into the corresponding β-(mesyloxy) imines. Reaction of these α,α-dichloro-α-(mesyloxy) ketimines with potassium cyanide or sodium borohydride in methanol furnished a variety of 2-cyano- and 2-methoxy-3,3-dichloroazetidines in a stereoselective manner. Reduction of β-(mesyloxy) imines with sodium cyanoborohydride followed by cyclization with potassium carbonate in DMSO yielded 3,3-dichloroazetidines as well.
Experimental and computational study of the conrotatory ring opening of various 3-chloro-2-azetines
Mangelinckx, Sven,Van Speybroeck, Veronique,Vansteenkiste, Peter,Waroquier, Michel,De Kimpe, Norbert
, p. 5481 - 5488 (2008/12/20)
(Chemical Equation Presented) A combined experimental and theoretical study is presented on 2-azetines, a class of azaheterocyclic compounds, which are difficult to access but have shown a unique reactivity as strained cyclic enamines. New highly substituted 2-azetines bearing aryl substituents at the 2- and 4-position were synthesized from 3,3-dichloroazetidines. Whereas 2-aryl-3,3-dichloroazetidines gave stable 2-aryl-3-chloro-2-azetines upon treatment with sodium hydride in DMSO, 2,4-diaryl-3,3-dichloroazetidines showed a remarkably different reactivity in that they afforded benzimidoyl-substituted alkynes under similar mild treatment with base. The formation of the alkynes involves electrocyclic ring opening of intermediate 2,4-diaryl-3-chloro-2- azetines and elimination of hydrogen chloride. Ab initio theoretical calculations confirmed the experimental findings and demonstrated that the 4-aryl substituent is responsible for this remarkably enhanced reactivity of 2-azetines toward electrocyclic conrotatory ring opening by a significant decrease in reaction barrier of about 30 kJ/mol. This activation effect by an aryl group in the allylic position toward electrocyclic ring opening of unsaturated four-membered rings is of general importance since a similar increased reactivity of 4-aryloxetes, 4-arylthiete-1,1-dioxides, and 3-arylcyclobutenes has been reported in literature as well.
