Stereochemistry and reactivity in interconversions of three- and four-co-ordinate imino-derivatives of sulphur

摘要

2120 J.C.S. Perkin IStereochemistry and Reactivity in lnterconversions of Three- and Four-co-ordinate Imino-derivatives of Sulphur tBy Stefan0 Colonna, lstituto de Chimica Industriale, Universitil de Milano, ItalyCharles J . M. Stirling," School of Physical and Molecular Sciences, University College of North Wales,Optically pure sulphoxides have been converted into N-phthalimidosulphoximides by treatment with N-amino-phthalimide and lead tetra-acetate. Sulphoxides are regenerated in high yields and optical purities on treatmentwith sodium ethoxide or hydrazine in ethanol and it is suggested that each step in these two-step cycles occurswith retention of configuration at sulphur. No attack occurs a t the carbon-carbon double bond in formation ofthe sulphoximide from p-tolyl vinyl sulphoxide.Reactions of S-vinyl- and of S-@-substituted-ethyl-sulphimides have been briefly investigated in a qualitativeevaluation of the activating effects of the sulphonylimino-sulphur group on elimination and addition reactions.BangorTHE reactivity and stereochemistry of simple imino-derivatives of sulphur has been widely inves4igated.lMuch attention has been focused on the interchange ofligands at sulphur and rather less on the effect of imino-sulpliur groups on reactivity at more distant molecularsites. In this paper we report on two aspects of imino-sulphur chemistry : first, the stereochemistry of form-ation of N-phthalimidosulphoximides (1) from opticallyactive sulphoxides and the subsequent regeneration ofthe sulphoxides; and secondly, the effect of the three-co-ordinate imino-sulphur group in sulphimides on thereactivity of leaving groups situated p to it and upon theelectrophilic reactivity of an adjacent carbon-carbondouble bond.0( 1 12 a; R1=CH Ph R=p -MeC Hb; R =CH:CH2 R =p-MeC6HLc; R'=a-Naphthyl, RLp-MeC H2 6 .41 26 G1 2 d; R= CH Ph, R=CH2CH2CI22e;R'= CH,CH2Cl R =p-MeC H6 LSuZ+hoximides.-Several methods are available forthe conversion of sulphoxides into sulphoximides. Theseinclude treatment with a sulphonyl azide and copper,2with hydrazoic acid,3 and with a sulphonamide togetherwith lead tetra-acetate and a mild base such as triethyl-amine.* A particularly simple procedure has been re-ported by Rees and his collaborators5 which involvestreatment of the sulphoxide with N-aminophthalimidePart of this work has been reported in a preliminary com-munication: S.Colonna and C. J. M. Stirling, Chem. Comm., 1971,1591.T. R. Williams, R. E. Booms, and D. J. Cram, J . Amer.Cliem. SOC., 1971, 93, 7338.D. J. Cram, J. Day, D. R. Rayner, D. M. von Schriltz,D. J. Duchamp, and D. C. Garwood, J . Amer. Claern. SOC., 1970,91, 7369.R. Fusco, and A. Tenconi, Chimica > Industria, 1965, 1, 61.and lead tetra-acetate in dichloromethane; a synthesiswhich probably involves nitrene intermediates.6 Wehave now applied this procedure to a number of sulph-oxides including three optically active compounds;the results are in the Table; yields are excellent and thesulphoximides obtained from the active sulphoxides arethemselves optically active.Particularly interesting inthis respect is the conversion of optically active +-tolylvinyl sulphoxide into the a@-unsaturated sulphoximide(lb). No competing reactions were observed whichcould have been associated with the carbon-carbondouble bond which, in this case, is susceptible to electro-philic,' nucleophilic,s and radical addition. Nitreneaddition is a familiar reaction type for alkenes.10The N-phthalimidosulphoximides (e.g. S-9-tolyl-S-vinyl-) were stable to concentrated sulphuric acid forshort periods (ca. 30 min) at room temperature; con-ditions in which AT-+-tolylsulplionylsulphoximides arereadily hydrolysed to the simple sulphoximides. Withlonger reaction times, however, decomposition occurred.Treatment of the N-phthalimidosulphoximides withsodium ethoxide or with hydrazine in ethanol, however,regenerated the sulphoxide with concurrent formation,in the case of sodium ethoxide, of the half-ester ofphthalic acid.In the case of the S-vinylsulphoximide,the adduct with ethanol, 2-ethoxyethyl 9-tolyl sulph-oxide, was isolated as the regeneration product. Whenoptically active sulphoximides were used, the sulph-oxides were obtained in good yield and with high opticalpurity (Table). These observations established thatboth formation of the sulphoximides from the sulph-oxides and their regeneration occurs with high stereo-specifrcity. Clearly, in this two-reaction cycle, bothreactions occur with retention or both with inversion ofconfiguration.We favour double retention in the cycle ;Cram and his co-workers,2 have shown that treatmentof methyl p-tolyl sulphoxide with toluene-$-sulphonyl4 T. Ohashi, K. Matsunaga, M. Okalhara, and S. Koniori,Synthesis, 1971, 96, and references cited.5 C. W. Rees and M. Yelland, J.C.S. Pevkin I , 1972, 77.6 D. S. Atkinson and C. W. Rees, Chew Comm., 1967, 1230.7 D. J. Abbott and C. J. M. Stirling, Chem. Comm., 1971, 472.D. J. Abbott, S. Colonna, andC. J. M. Stirling, Chem. Comm.,9 C. Walling, ' Free Radicals in Solution,' Wiley, New York,10 H. Kwart and -4. A. Khan, J . Anzev. Chern. SOC., 1967, 89,1971, 471.1957.19511974 2121azide and copper give the sulphoximide with retentioiz with trietliylamine in toluene.As would be expectedof configuration. For these reactions, copper-nitrene from this observation, a three-co-ordinate imino-sulphurcomplexes l1 arc probably involved and the mechanism group activates the adjacent carbon-carbon double bondis fonnally similar to that of the N-aminophthalimide of the aP-unsaturated sulphimide towards nucleophilicreaction. The ethoxide reaction probably occurs in addition. The sulphimide (3b) on treatment withseveral stages and the yields of sulphoxide obtained are ethanolic sodium ethoxide gave the ethoxy-derivativevirtually quantitative (4a), which is also formed directly by similar treatmentInterconversion of sulphosides and N-phthaliniiclosulphoximidesYield fromsulohoxid eFound (yo) - Compound M.p.("C) aD (") 'c H(14 89 137 -19" 67.2 4.602 184 -26.8 ' 69.3 4.370 163C +30" 62.2 4.480 113 56.2 4.0100 143 56-5 4.30 c 1, CHCI,. Before purification. liacemic 111.p. 191.5".(1b)( 1 4( 1 4(14f Hydrazine reaction.In correction of our earlier report,* nitrogen is evolvedin the ethoxide reactions. These were carried out underoxygen at 1 atm. and treatment of samples of the gasspace with alkaline pyrogallol showed that stoicheio-metric quantities of nitrogen were obtained. Hydrazinewas sought by a procedure which would have detected itsformation in yields >5.In relation to these results, it has been shown thatalkaline hydrolysis of a szd$lzinzide involves iizoersion ofconfiguration at sulphur.2SzzZphirnides.-A qualitative examination has beenmade of the electronic effects of three- and four-co-ordinateimino-sulphur groups, with particular reference to thecomparison of the electronic effects of these groups withsulphinyl and sulphonyl groups.We prepared the N-9-tolylsulphonylsulphimides (2) from 2-halogenoethylsulphides by reaction with chloramine T (Scheme). TheNone was found.NTs ,( 2 )a,R=PhCH - 2>b,Rhp- Me C6HL-3NEtO- R' SCH:CH2p-MeC H SCH2CH2R2 11 "I Or '!jHio" NTsN Ts(I)a,RzOEt;b, R