C. Aurell, Staffan Karlsson, F. Pontén
Sep 9, 2014
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Influential Citations
6
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Journal
Organic Process Research & Development
Abstract
A synthesis of N-Boc (2R)-1,4-oxazepane-2-carboxylic acid 1 has been developed in 39% yield over seven steps starting from methyl (2R)-glycidate 2. The key step was a lipase-catalyzed regioselective lactamization of amino diester 5 into seven-membered lactam 6. The transformation was performed using SpinChem rotating flow cell technology which simplified the work up and the recycling of the enzyme. Subsequent N-Boc protection followed by chemoselective borane reduction of the lactam moiety afforded 4-tert-butyl 2-methyl (2R)-1,4-oxazepane-2,4-dicarboxylate 8. Finally, hydrolysis mediated by LiBr/Et3N in wet acetonitrile yielded the title compound (2R)-4-(tert-butoxycarbonyl)-1,4-oxazepane-2-carboxylic acid 1.