L. S. zyxwvutsrqpon Boulos, I. T. Hennawy, M. H. N. Arsanious zyxwvut 351 Reactions of Phosphites with 1,4-Benzoquinone Monoimines Leila Sadek Boulos*, Ibtisam Tadros Hennawy and Mona Hazkial Nasr Arsanious National Research Centre, Dokki, Cairo, Egypt Received June 15, 1992 Key Words: 1 ,4-Benzoquinone monoimine zyxwvut I Phosphites I Phosphates I Phosphonates Trimethyl phosphite (2 a) reacts with N-(phenylsulfony1)-l,4- benzoquinone monoimine (1 a) to give the respective phos- phonate 3c, phosphates 3d. 3e and the alkylated products 3 a and 3 b. The reaction of triethyl phosphite (2 b) with the same quinone imine 1 a yields only the phosphate adduct 3f and the amide 3 g. Triisopropyl phosphite (2 c) reacts with 1 a to form the alkylated product 3 h. Trimethyl phosphite (2 a) gives the phosphate 4a on reaction with N-(methylsulfony1)- 1,4-benzoquinone monoimine (lb). In case of the reaction of triethyl and triisopropyl phosphites (2 b, c) with 1 b only the respective alkylated products 4b-d are obtained. A mechan- ism is proposed to explain the formation of the new adducts. Previous work has that trialkyl phos- phites react with p-quinones and p-quinone imines to yield phosphates and phosphoramidates, respectively. Recently, we have that trialkyl phosphites react with zyxwvu N- zyxwvu (phenylsulfonyl)-l,4-naphthoquinone monoimine to give the corresponding phosphonate adducts. Since p-benzoquinone monoimines 1 a, b have a structure analogous to that of p-naphthoquinone monoimine, it is of interest to examine their behavior towards these phosphites in order to prove if the carbonyl or imino center is attacked preferentially by phosphorus. We have found that the reaction of N-(phenylsulfony1)-p- benzoquinone monoimine (1 a) with three mole equivalents of trimethyl phosphite (2a) in benzene proceeds at room temperature to give five adducts formulated as 3a-3e (cf. Scheme 1). The alkylated products 3a and 3b have been identified by compatible analytical and mass spectroscopic results (cf. Experimental). Structure elucidation of dimethyl zyxwvu { 2-hydroxy-5-[methyl(phenylsulfonyl)amino]phenyl} phos- phonate (3 c) is based on the following evidence: (i) Compound 3c exhibits 6 = +23.23 in its 31P-NMR spectrum which clearly indicates a phosphonate struc- t~re[~,~]. - (ii) The IR spectrum of 3c exhibits strong absorption bands at 3450 cm-' (hydroxyl), 1230 cm-' ( >P=O)[sl, (P-O-CH3)[*l and 1447 cm-' (P-Ph)r91. Moreover, its IR spectrum lacks both the carbonyl and C= N absorption bands appearing in the spectrum of la at 1656 and 1586 cm-', respectively. - (iii) Compound 3c re- sponds positively to the ferric chloride test and dissolves in 10% aqueous alkali. - (iv) The 'H-NMR spectrum (400 MHz) of compound 3c exhibits signals at 6 = 3.73 [d, 7.65-6.78 (m, 5 H, aromatic H), 10.16 (s, 1 H, hydroxyl, exchangeable with DzO), 6.88 (dd, JH~ = 14.85 Hz, JHH = 2.4 Hz, 1 H, 6-H) and at 6.90, 6.91 (d, JHH = 7.65 Hz, 2 H, 3-H and 4-H). The 13C-NMR spectrum furnishes strong evidence in support of the phosphonate structure 3c. The 13C-NMR JHp = 11.55 Hz, 6 H, P(OCH3)2]"Ol, 3.14 (s, 3 H, NCH3), spectrum of 3c in CDC13 shows a doublet at 6 = 128.25 with the coupling constant Jbc = 99.8 Hz ascribed to C-1 attached to phosphorus. The spectrum of 3c also shows signals at 6 = 53.16 [P(OCH3),] and 38.142 (NCH3). These values are in full accord [l21 with structure 3c. Adduct 3c regenerates the starting quinone monoimine 1 a and the re- spective dialkyl hydrogen phosphite, when subjected to py- rolysis. The structures of the other isolated compounds 3d and 3e have been elucidated as follows: The 31P-NMR spectrum of dimethyl 4-[methyl(phenylsulfonyl)amino]phenyl phos- phate (3 d) supports the phosphate structure since it exhibits a sharp signal at 13 = -0.277 (vs. H3P04) which corre- sponds to a phosphate and not to phosphonate or phos- phoramidate add~cts[~*']. Its IR spectrum reveales the ab- sence of C=O and C = N absorption bands recorded for 1 a at 1656 and 1587 cm-', respectively. The spectrum shows, however, strong absorption bands at 1280 cm-' (> P=O) and at 1050 cm-' (P-0-CH3). The 'H-NMR spectrum of 3d exhibits signals at 6 = 3.92 [d, JHp = 11.55 Hz, 6 H, 2 H), 6.34 (d, JHH = 8.25 Hz, 2 H), 7.26-7.6 (m, 5 H, aro- matic H). The mass spectrum of 3d yields a prominent ion peak at zyxwv mlz = 371 (M+, 9%). The structure of compound 3e was deduced from 31P- NMR (6 = -0.27), IR, 'H-NMR, I3C-NMR and mass spectral data (cf. Experimental). Treatment of adduct 3e with diazomethane solution in ether in the presence of methanol results in the formation of 3d (m. p., mixed m. p. and comparative IR spectra, cf. Experimental). We propose the reaction course depicted in Scheme 2 to account for the reaction of trimethyl phosphite (2a) with quinone mono- imine la. Adduct 3c can be obtained via a Michaelis addition [l3J41 of trimethyl phosphite to quinone monoimine la to give the dipolar intermediate A (path A), which yields by mi- gration of a methyl group the phosphonate adduct 3c. On the other hand, primary nucleophilic attack by the phos- P(OCH3)2], 3.23 (s, 3 H, NCH3), 6.67 (d, JHH = 8.25 Hz, Liebigs Ann. Chem. 1993, 351 -354 zyxwvuts 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1993 0170-2041/93/0404-0351 $ 10.00+.25/0