Enantiopure synthesis of dihydrobenzo[1,4]-oxazine-3-carboxylic acids and a route to benzoxazinyl oxazolidinones.

Rajesh Malhotra, Tushar K Dey, Sourav Basu, Saumen Hajra

Organic & biomolecular chemistry 2015 Mar 21

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A two step protocol is developed for the efficient synthesis of enantiopure N-Boc-dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids 4 from serine derived cyclic sulfamidate via intramolecular arylamination. The RuPhos Palladacycle along with additional RuPhos ligand is found to be an efficient catalyst for the arylamination of β-(2-bromoaryloxy)amino acids 3 to provide easy and direct access to a variety of dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids 4 with complete retention of enantiopurity in moderate to high yields. Dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids are not only important unnatural amino acids, but are key precursors for the synthesis of important compounds such as benzoxazinyl oxazolidinones. A general approach for the synthesis of benzoxazinyl oxazolidinone is presented.

Citation

Rajesh Malhotra, Tushar K Dey, Sourav Basu, Saumen Hajra. Enantiopure synthesis of dihydrobenzo[1,4]-oxazine-3-carboxylic acids and a route to benzoxazinyl oxazolidinones. Organic & biomolecular chemistry. 2015 Mar 21;13(11):3211-9