161362-39-6Relevant articles and documents
A new strategy for the stereoselective synthesis of unnatural α-amino acids
Gallos, John K.,Sarli, Vassiliki C.,Massen, Zoe S.,Varvogli, Anastassia C.,Papadoyanni, Constantina Z.,Papaspyrou, Sofia D.,Argyropoulos, Nicolaos G.
, p. 565 - 574 (2007/10/03)
A new method for the synthesis of racemic non-proteinogenic α-amino acids has been developed, which involves (i) hetero-Diels-Alder addition of ethyl 2-nitrosoacrylate to electron rich alkenes such as enol ethers, enamines and allylsilanes, (ii) NaCNBH3 reduction of the CN bond in the oxazines thus generated, the stereochemistry of the products being controlled by epimerisation of the thermodynamically less stable isomer to the more stable one, (iii) protection of the N-H group as N-Boc and (iv) finally, N-O bond cleavage of both free and protected products to give proline or bis-homoserine derivatives, respectively. An example with concomitant reduction of the carboxylate group, resulting in the formation of the respective amino alcohol is reported. Applying this methodology to a homochiral enol ether, the protected parent d-proline was prepared in enantiomerically pure form, whereas the asymmetric synthesis of the respective bis-homoserine was unsuccessful. Graphical Abstract.
An efficient and simple synthesis of 3,4,5,6-tetrahydro-2H-1,2-oxazines by sodium cyanoborohydride reduction of 5,6-dihydro-4H-1,2-oxazines
Zimmer,Arnold,Homann,Reissig
, p. 1050 - 1056 (2007/10/02)
3,4,5,6-Tetrahydro-2H-1,2-oxazines are prepared by reduction of the corresponding 5,6-dihydro-4H-1,2-oxazines with sodium cyanoborohydride as the reducing agent in acetic acid. This reaction gives the 3,5-disubstituted compounds 2a-c, 2f-g, and 5a,b with
