Base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates to 4-alkylidene-2-oxazolidinones

Ramesh, Ramapanicker ; Chandrasekaran, Yogesh ; Megha, Rajendran ; Chandrasekaran, Srinivasan (2007) Base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates to 4-alkylidene-2-oxazolidinones Tetrahedron, 63 (37). pp. 9153-9162. ISSN 0040-4020

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00404...

Related URL: http://dx.doi.org/10.1016/j.tet.2007.06.066

Abstract

The base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates is studied in detail. The effect of various bases and solvents on the efficacy of this cyclization reaction is analyzed and a new base-solvent system (LiOH in DMF) for effective cyclization of these carbamates is reported. A number of differentially substituted O-propargyl carbamates were cyclized to the corresponding 2-oxazolidinones under these conditions. The reaction conditions reported here are mild and no side reactions were observed in any of the substrates studied. A propargyl carbonate group was unaffected during the course of the cyclization of the O-propargyl carbamate group. The propargyl carbamates were prepared from the corresponding alkyl or aryl amines and the corresponding propargyl chloroformate, resulting in oxazolidinones diversely substituted at the nitrogen atom. N-Aryl-O-propargyl carbamates cyclized readily to the corresponding oxazolidinones with LiOH in DMF, whereas N-alkyl-O-propargyl carbamates reacted slowly under the same conditions. O-Propargyl carbamates substituted at the 1-position tend to cyclize faster whereas those substituted at 3-position cyclize considerably slower than the unsubstituted carbamates.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Carbamates; Oxazolidinones; Cyclization; Solvent Effects; Chloroformates
ID Code:7228
Deposited On:25 Oct 2010 12:07
Last Modified:01 Feb 2011 09:22

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