Synthesis of chiral, nonracemic methyleneaziridines derived from β-amino alcohols

Asymmetric Synthesis of Protected 1,2-Amino Alcohols Using tert-Butanesulfinyl Aldimines and Ketimines

“…Conversion of products 3a , 3b , 3d , 3e , 4d , and 4f 9 to the respective 1,2-amino alcohols or O -benzyl 1,2-amino alcohols and comparison to literature optical rotation values revealed that the sense of induction for additions to α -benzyloxy or α -silyloxy N -sulfinyl aldimines is opposite from that previously observed for additions to alkyl and aryl substituted N -sulfinyl imines , For Grignard additions to alkyl and aryl N -sulfinyl aldimines, attack occurs exclusively from the Si face of the imine (eq 5), where the reaction is postulated to occur through a six-membered transition state resulting from the coordination of the E -imine with the incoming nucleophile .…”

“…Absolute configuration was determined through sulfinyl group cleavage to afford ( R )-2-benzyloxy-1-phenylethylamine: [ α ] 23 D = −24.6 ( c = 1.00, CHCl 3 ) [lit. : [ α ] 23 D = −28.3° ( c = 1.10, CHCl 3 )] …”

One-Pot Cascade Synthesis of Fused Nitrogen-Containing Heterocycles in Aqueous Media – Utility of N-Protective Groups in Intramolecular Diels–Alder Reaction of Furan

“…Treatment of primary amines 7 (n = 1, n = 2, R = H, Me) with 2,3-dibromopropene or 2,3-dichloropropene in the presence of potassium carbonate in boiling tetrahydrofuran provided the corresponding (bromoallyl)-and (chloroallyl)amines 3 in good yields (Scheme 2). 16 All subsequent nitrogen-protection and cycloaddition reactions were performed in a one-pot procedure and monitored by thin-layer chromatography until no further progress was detected ( Table 1). Reactions involving sulfonyl protecting groups (mesyl, nosyl, and tosyl) and the Cbz group were carried out in water in the presence of potassium carbonate at 98-100 °C under continuous stirring for four days (entries 1-6, 12, and 13).…”

Observations on the ring opening reactions of 2-methyleneaziridines with acid chlorides and alkyl chloroformates

“…2 We have used this methodology to make a variety of chiral, nonracemic methyleneaziridines which we hope may ultimately find use in asymmetric synthesis. 3, 4 For example, we have prepared methyleneaziridine (S)-2 as a single enantiomer by ring closure of the corresponding N-(2-bromoallyl)amine 1, itself readily derived from (S)-α-methylbenzylamine (Scheme 1). 3 Few other general methods for the preparation of 2-methyleneaziridines currently exist.…”