title: N,N-DIIsopropyl-N-phosphonyl imines lead to efficient asymmetric synthesis of aziridine-2-carboxylic esters.
abstract: Highly diastereoselective asymmetric synthesis of chiral aziridine-2-carboxylic esters is reported for 20 examples with good yields (51-87%) and excellent diastereoselectivities (>99:1 dr for most cases). The modified N-phosphonyl imines have proven to be superior to previous imine auxiliaries for the aza Darzens reaction by using a secondary isopropyl group to replace the primary benzyl group for N,N-diamino protection. In the meanwhile, a special operation by slowly adding the pre-cooled imine solution at -78 °C into the preformed β-bromo lithium enolate mixture at this temperature in the presence of 4 Å molecular sieves was found to be crucial in terms of yields and diastereoselectivity. The present method can provide an easy and general access to β-hydroxy α-amino acids and other important amino building blocks.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA.
authors.forename: Padmanabha V
authors.initials: PV
authors.lastname: Kattamuri
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Xiong
authors.forename: Yi
authors.initials: Y
authors.lastname: Pan
authors.forename: Guigen
authors.initials: G
authors.lastname: Li
mesh_terms: D001388:Aziridines / Q000138:chemical synthesis* / Q000737:chemistry; D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D001388:Aziridines; D004952:Esters; D007097:Imines; C073440:aziridine-2-carboxylic acid
references.citation: Angew Chem Int Ed Engl. 2009;48(39):7224-6
references.pmid: 19718735
references.citation: J Org Chem. 2006 Nov 24;71(24):8993-9003
references.pmid: 17109522
references.citation: Org Biomol Chem. 2010 Jul 21;8(14):3251-8
references.pmid: 20502774
references.citation: Bioorg Med Chem Lett. 2009 Jul 15;19(14):3967-9
references.pmid: 19297153
references.citation: Chem Rev. 2007 May;107(5):2080-135
references.pmid: 17488062
references.citation: J Org Chem. 2003 Mar 21;68(6):2410-9
references.pmid: 12636410
references.citation: Chem Biol Drug Des. 2009 Feb;73(2):203-8
references.pmid: 19207422
references.citation: Chem Biol Drug Des. 2008 Aug;72(2):120-6
references.pmid: 18631372
references.citation: Beilstein J Org Chem. 2012;8:2124-31
references.pmid: 23243474
references.citation: J Med Chem. 1990 Aug;33(8):2157-62
references.pmid: 2197412
references.citation: Org Lett. 2006 Jul 6;8(14):3129-32
references.pmid: 16805569
references.citation: J Org Chem. 2011 Apr 1;76(7):2204-13
references.pmid: 21381724
references.citation: Biopolymers. 1997;43(3):219-66
references.pmid: 9277134
references.citation: J Antibiot (Tokyo). 1954 Aug;7(4):107-12
references.pmid: 13211477
references.citation: J Antibiot (Tokyo). 1986 Nov;39(11):1527-32
references.pmid: 3793621
references.citation: Chem Soc Rev. 2012 Jan 21;41(2):643-65
references.pmid: 21894345
references.citation: J Antibiot (Tokyo). 1991 Apr;44(4):403-14
references.pmid: 2032949
references.citation: J Org Chem. 1999 Nov 26;64(24):8929-8935
references.pmid: 11674800
references.citation: Org Biomol Chem. 2010 Mar 7;8(5):1091-6
references.pmid: 20165799
references.citation: J Am Chem Soc. 2011 Dec 7;133(48):19342-5
references.pmid: 22081884
references.citation: J Org Chem. 2007 Sep 14;72(19):7199-206
references.pmid: 17705431
references.citation: J Med Chem. 1971 Feb;14(2):103-9
references.pmid: 5544392
references.citation: Chem Biol Drug Des. 2008 Mar;71(3):216-23
references.pmid: 18251775
references.citation: J Antibiot (Tokyo). 1995 Mar;48(3):217-21
references.pmid: 7730155
references.citation: J Org Chem. 2011 Apr 15;76(8):2792-7
references.pmid: 21405041
references.citation: Chem Rev. 2002 Jul;102(7):2477-95
references.pmid: 12105933
references.citation: J Org Chem. 2007 Apr 27;72(9):3211-7
references.pmid: 17397222
references.citation: J Antibiot (Tokyo). 1987 May;40(5):594-9
references.pmid: 3610818
references.citation: Org Biomol Chem. 2012 Mar 21;10(11):2326-38
references.pmid: 22311107
references.citation: Beilstein J Org Chem. 2009 Jul 08;5:33
references.pmid: 19777135
references.citation: J Med Chem. 1991 Jul;34(7):2281-6
references.pmid: 1906109