1. Efficient Chemoenzymatic Synthesis of (2 S,3 R)-3-Hydroxy-3-Methylproline, a Key Fragment in Polyoxypeptin A and FR225659
Xiao Zhang, Hans Renata Tetrahedron. 2019 Jun 14;75(24):3253-3257. doi: 10.1016/j.tet.2019.04.009. Epub 2019 Apr 5.
We report an efficient synthesis of protected (2S,3R)-3-hydroxy-3-methylproline that proceeds in three steps with complete stereoselectivity. This route represents a significant improvement over previous approaches to this noncanonical amino acid. Key to this success is the development of a one-pot chemoenzymatic procedure for the preparation of (2S,3S)-3- methylproline from L-isoleucine. This work lays the foundation for future chemoenzymatic syntheses of polyoxypeptin A and FR225659.
2. Stereoselective synthesis of (2S,3R)-α-hydroxy-β-amino acids (AHBAs): valinoctin A, (2S,3R)-3-amino-2-hydroxydecanoic acid, and a fluorescent-labeled (2S,3R)-AHBA
Sharad Chandrakant Deshmukh, Pinaki Talukdar J Org Chem. 2014 Nov 21;79(22):11215-25. doi: 10.1021/jo501751u. Epub 2014 Oct 31.
We report the stereoselective synthesis of an alkynyl side-chain containing (2S,3R)-α-hydroxy-β-amino acid ((2S,3R)-AHBA) analogues. The Cu(I)-catalyzed reactions of (R)-glyceraldehyde acetonide and dibenzylamine with terminal alkynes provided the corresponding (2S,3R)-α-amino alcohols with good-to-excellent diastereoselectivity. Subsequent chemical transformations provided easy access to the alkynyl side-chain containing (2S,3R)-AHBAs. The utility of the methodology was demonstrated by the stereoselective synthesis of valinoctin A and (2S,3R)-3-amino-2-hydroxydecanoic acid ((2S,3R)-AHDA). Photophysical properties and cell permeability of a pyrene-labeled (2S,3R)-AHBA were also determined.
3. (2S,3R)-2-[(4-Ethyl-2,3-dioxopiperazin-1-yl)carbonyl-amino]-3-hydroxy-butyric acid monohydrate
Chun-Xiang Ji, Yong-Tao Cui, Dong-Ling Yang, Cheng Guo Acta Crystallogr Sect E Struct Rep Online. 2008 Jun 19;64(Pt 7):o1292. doi: 10.1107/S1600536808017832.
In the title compound, C(11)H(17)N(3)O(6)·H(2)O, an important building block of the medicine cefbuperazone sodium, the piperazine ring adopts a screw-boat conformation. Inter-molecular O-H⋯O and intra-molecular N-H⋯O hydrogen bonds are observed. The water mol-ecule participates as both donor and acceptor in this framework.
