反应详情

1-t-Butyldimethylsilyl-4-tritylthioazetidin-2-one (1) (9.18 g, 20 mmol) was reacted with an approximately 1:1 mixture of ethyl 1- and 2-methyltetrazole-5-carboxylate (3.94 g, 24.8 mmol) (prepared by treating ethyl tetrazole-5-carboxylate [D. Moderhack, Chem. Ber., 1975, 108, 887]with excess diazomethane [cf 0. Gryszkiewicz-Trochimourski, Compt. Rendu, 1958, 246, 2627]) using the method described in Preparation 4(a). The crude reaction mixture was chromatographed on silica eluting with ethyl acetate/hexane mixtures to give two fractions. The less polar fraction contained a regioisomer of the title azetidinone (123) (3.48 g, 30%) νmax (CH2Cl2) 1750, 1690 cm-1 ; δ(CDCl3) 0.34 (6H, s), 1.00 (9H, s), 4.10 (3H, s), 4.90 (2H, s), 6.77-7.50 (15H, m); The more polar fraction contained the other regioisomer of the title compound ( 124) (3.5g, 30%) (mp. 158°-161°, needles ex ether/hexane) νmax (CH2Cl2) 1750, 1700 cm-1 ; δ(CDCl3) 0.37 (6H, s), 1.00 (9H, s), 4.37 (3H, s), 4.57 (1H, d, J2 Hz), 4.97 (1H, d, J2 Hz), 6.80-7.60 (15H, m). (Found C, 65.3; H; 6.3; N, 12.2; S, 5.6. C31H35N5O2SSi requires C, 65.4; H, 6.2; N, 12.3; S, 5.6%).

1. customprepared
2. customThe crude reaction mixture
3. customwas chromatographed on silica eluting with ethyl acetate/hexane
4. customto give two fractions