Oxirane carboxamides

Scheme 39 Coupling of oxirane carboxamides and vinyl bromides...

Wang disclosed an efficient copper-catalyzed cross-coupling of oxirane carboxamides with vinyl bromides (Scheme 39) [127]. After screening studies, they came to a similar system to that reported by Ma for vinylations of amides. In most cases, the stereoselectivity of the process was good to high with the ratio of Z-enamide over -enamide ranging from 85 15 to 95 5. Notably, the protocol was successfully applied in the synthesis of valuable Clausena alkaloids. 

The Passerini reaction between a-chloroketones, isocyanides, and carboxylic acids afforded a-acyloxy-jS-chlorocarboxamides 52, which, on treatment with an excess of powdered KOH in tetrahydrofuran, underwent O-deacylation followed by a Darzens-type O-alkylation to give the functionalized oxiranes 53. When carboxamides 52 were treated with an excess of CsF, with or without a phase-transfer catalyst, a different ring closure took place to afford 3-acyloxy-2-azetidinones 54 in high yields (Scheme 2.21) [46]. 

R. erythropolis (previously R. rhodochrous) AJ270, which has been utilized in many enantioselective transformations of nitriles such as cyclopropane, oxirane, and aziridine analogs [10, 12], was recently proved to catalyze the enantioselective hydrolysis of azetidine-2-carbonitriles [13] and P-lactam carbonitriles also [14] (Figure 11.2). Carboxylic acids and carboxamides were also obtained with significant enantiomeric excesses from 3-hydroxy-4-aryloxybutanenitriles and 3-hydroxy-3-arylpropanenitriles (Figure 11.3) using R. rhodochrous ATCC BAA-870 [15], which is more elaborately discussed in Chapter 14. 

R. erythropolis AJ270 Cyclopropane, oxirane, aziridine carbonitriles Enantiopure trans- and cis-cyclopropanecarboxylic acids and carboxamides, oxirane and aziridine carboxamides Chemoenzymatic synthesis of various building blocks [100-104]... 

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