Reactions d'addition nucléophile sur les cétones. Rǒle des facteurs stériques à longue distance dans les réactions d'addition de l'ion sulfite et de l'hydroxylamine

Abstract

566 B. Boyer et al. 1 Reactions d'addition nucleophile sur les catones14; yield 28%; oil; 'H-NMR (CDCI,): 6 = 1.26 and 1.43 (s, t-Bu), 6 = 1.16 and 1.29 (t, J = 7 Hz, N-C-CH,), 6 = 3.28 and 3.57 (q, J = Hz, N-CH,-C), 6 = 7.33 and 7.63 (d, J = 2.4 Hz, 2 arom. H) and 6 = 12.20 (s, OH). IR (CCI,): 1630 and 1655 cm-' (C=O) and 3400 cm-' (broad) (OH). UV (hexane) h,,,/nm (E/m2.mol-'): 219 (sh) (1750), 267 (980) and 351 (400). MS (70 eV) m/e (%; fragment): 333 (18; M?) and 233 (100; M? -CONEt,). I3C NMR (CDCI,): 6 = 197.4 and 165.2 (C=O). Treatment of the carboxamides 8 and 9 with BF,.OEt,. Formation of y-lactoncs 20,21,22 and 24 and of the furandione 23Treatment of 8 in pure CHCI,. To a well stirred solution of the carboxamide 8 in pure CHCI, BF,,OEt, was added (for reaction conditions see Table I). After work up of the dark reaction mixture as already described, the crude y-lactone 22 was purified by chromatography (SiO,/benzene) followed by recrystallisation from CHCI,/ hexane (yield 96 %). No needles of a tetrafluoroborate separated.The isolation of the furandione 23 is described below.Treatment of 8 in alcohol or ethanethiol containing CHCI,. In this case the solvent CHCI, contained 1 % methanol, ethanol or ethanethiol (for reaction conditions when methanol or ethanol was present see Table I). After work up, as already described, the y-lactones 20a, 2la and 22 were separated by chromatography (SiO,/benzene) in yields dependent on the conditions (2121 and 22 could not be separated from each other). The y-lactone 20a was recrystallised from CHClJhexane. See Table Ill for details and spectroscopical data of 2Oa and 21a. The salt [Et,NH,]'[BF,]separated from the reaction mixture and was isolated by filtration of the crude reaction mixture followed by several washings with CHCI,: colourless needles, m.p. 171-172°C. C,H,,BF,N (160.950): calcd. C, 29.85; H, 7.51; B, 6.72; F, 47.21; N, 8.70; found C, 29.7; H, 8.2; B, 6.3; F, 45.8; N, 8.7. The furandione 23 separated only from the reaction mixture at concentrations of 0.19 M. After filtration of the crude reaction mixture, 23 was obtained in a pure state by recrystallisation from hot benzene (yield 70 %). When ethanethiol was present the y-lactone 24 was isolated (yield 80 %) after stirring during 60 min at OOC. It was not possible to isolate an intermediate i n this case.Treatment of 9 in CHCI, containing ethanol.-After treatment of 0.0025 mol of9 in CHCI, containing ethanol (35 ml) with BF,.OEt, (1.42 g, 0.010 mol) and after stirring during 3 weeks at room temperature and work up as already described, the y-lactones 20b and 21b were isolated. Yields: 20b (R = Et) 18%; 21b (R = Et) 30%); 20b (R = i-Pr) 15%; 21b (R = i-Pr) 28%. The y-lactones were, after chromatography (SiO,/benzene), recrystallised from CHCl,/hexane. When pure 2lb was treated with BF,.OEt, under these reaction conditions an equilibrium mixture of 20b and 21b was isolated. See Table 111 for details and spectroscopical data of 20b and 21b. 22; yield 96%; m.p. 128.5-129"C; 'H-NMR (CDCI,): 6 = 2.15 (s, SMe), ...