Ramesh, Ramapanicker and Chandrasekaran, Yogesh and Megha, Rajendran and Chandrasekaran, Srinivasan (2007) Base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates to 4-alkylidene-2-oxazolidinones. In: Tetrahedron, 63 (37). pp. 9153-9162.
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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:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier Ltd.|
|Department/Centre:||Division of Chemical Sciences > Organic Chemistry|
|Date Deposited:||06 Feb 2008|
|Last Modified:||19 Sep 2010 04:42|
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