In the Search for New Anticancer Drugs, III+ Phosphorylated Diaziridine Derivatives George Sosnovsky* and Jan Lukszo Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, U.S.A. Z. Naturforsch. 38b, 884-894 (1983); received August 30/December 24, 1982 Phosphorylated Diaziridines, Synthesis, Anticancer Drugs, Leukemia P 388 Several N-diethoxyphosphoryl derivatives 7 of various diaziridines, and compounds 12, 15a, lob, 18 and 20, structurally related to TEPA (la) and spin labeled Thio-TEPA (lc) were synthesized. 0 Me 0 N-P(0Et)2 HC=NN-p(<]) o / NR ' • 11 f / 1 ? R-O-P-f N —C—R R X N—R CL N "2 Me Me 1 3 1 2 3 7: R . R = alkyl 12 15a: R = R =R =Me N-0 R2=H, alkyl 15b: R' = H,R2R3=-|CH2|5- Me Me In three cases, attempts to synthesize phosphorylated diaziridine derivatives resulted in rearrangements to give the corresponding phosphorylated hydrazone derivatives 11 h, Hi and 12. Me 0 CH = NN — P(0Et)j 11 h: x= H 11 i : x = ci 13C NMR spectroscopy was shown to be a valuable tool in distinguishing between the structures of diaziridine and hydrazone derivatives. The in vivo testing of five representa- tive compounds (7e, 12, 15a, 16 and 20) against murine lymphocytic leukemia P 388 showed a lack of antitumor activity of compounds 7e, 15 a, 16 and 20, and an activity of compound 12 as evidenced by a T/C value of 194 and a % ILS of 94, at a dose of 32 mg/kg. Introduction pounds, triethylenimine thiophosphoramide, Thio- In the past three decades, extensive studies [1-9] TEPA (lb, R = ethylenimine ring), has been used have been made in the search for new antineoplastic drugs containing the ethylenimine-(aziridine) moi- X ety. In particular, the phosphorus derivatives of P R type 1 a and 1 b containing two or three phosphorus- N-aziridine bonds, have been found to be effective alkylating anticancer agents [8, 10, 11]. It is pre- sumed [12, 13] that the alkylating reactions occur 1a : X = 0. R = or other groups at the nucleophilic centers of the heterobases of lb: X = S, R = £N, or other groups DNA causing cross linking and, thereby, the cessa- 1c: X =S, R = OR. tion of the replication of DNA. One of these com- + Part II: P. L. Gutierrez, M. Konieczny, and G. Sosnovsky, Z. Naturforsch. 36b, 1612 (1981). * Reprint requests to Professor Dr. G. Sosnovsky. ' Me 0340-5087/83/0700-0884/$ 01.00/0 Me G. Sosnovsky-J. Lukszo • In the Search for New Anticancer Drugs 885 clinically in the chemotherapy of certain cancers Results and Discussion [10]. Recently, it has been claimed [14-16] that As starting materials, several selected diaziridines nitroxyl labeled analogs of Thio-TEPA, such as 2 derived either from aldehydes or ketones were SL-O-TT (lc) [14, 15] and PAT-1 (Id) [16] have prepared by the reaction of hydroxylamine-O-sul- more desirable toxicological properties than the fonic acid with the corresponding ketone 5 or clinically used Thio-TEPA. aldimine 6 in the presence of either ammonia or the In contrast to the aziridines, the three-membered corresponding amine, following either the literature diaziridine ring system 2, containing two nitrogen procedures exactly [17, 30-33] or adapting a known atoms, was only scantily studied for possible anti- procedure [31, 34] to different starting materials, as cancer activity [17]. Although the diaziridine ring in the preparation of 2f and 2i. The N-phosphory- system was discovered only about two decades ago, the methods of preparation and the reactions of N-H diaziridines have been extensively explored [18-21]. \ H,N-0-S0,H H2N-Q-SO3H' c=o — f— <1 I . ,C=N-R' The diaziridine ring system can readily undergo R H2N-R' N—R H,N-R' C ring opening reactions either by an SN 1 mechanism 5 2 [22], involving carbonium ion intermediates (3), or 5a: R - i-Pr, R2 = R3 = Me 5b: R = R2 = R3 = Me 5c: R = H, R2R3 - —ICH2I5- H 5d: R = Me, R2R3 = —ICH2I5- NR © NR NR' 3 \ /i x \ R 6e: R = Et, R2 = Me, R = H V 6f: R = i-Pr, R2 = Et, R3 = H 2 ,2/ © \ / R NR' NH 6g: R = n-Bu, R2 - Et, R3 = H 6h: R = Me, R2 = Ph, R3 — H 6i: R = Me, R2 = p-Cl-C6H4, R3 = H 6j: R - C6HU, R2 - Ph, R3 — H by unspecified mechanisms, mediated by nucleo- philes, involving a reaction of the C-N-N group lated derivatives 7 were synthesized either by an [21], formed by ring opening of the diaziridine with adaptation of the Todd-Atherton method [35], i.e. a nucleophile. A series of such reactions, formally by the reaction of the appropriate diaziridine of the alkylation type, with reagents such as nitrones (2 a, e, f, g) with diethyl phosphite and carbon [23], enamines [24], cyclopropenone [25, 26], al- tetrachloride in the presence of triethylamine, or kynyl ketones [27], diphenyl ketene [28], and lead by the reaction of the diaziridine (2 e, g) with diethyl tetraacetate [29] have been reported. On the basis phosphorochloridate in the presence of triethyl- of such reactions, it is plausible to assume that the amine, similarly to the recently reported procedure diaziridines might be useful as alkylating antineo- [36], plastic agents. In 1967, Szantay et al. reported such a study [17]. Thus, three N-phosphorylated dia- 0 ziridine derivatives 4 were synthesized and tested (EtO)2PH/CCti/NEt3 ,N—P(0Et)2 2a,e.f,g (EtQ)2PCl/NEt3 4-R' n-Bu-N* .N-Bu-n 7a: R1 i-Pr, R2 = R3 = Me N —P—N 7e: R1 = Et, R2 = Me, R3 = H EtCH CHEt 71: R1 = i-Pr, R2 = Et, R3 = H 7g: R1 = n-Bu, R2 = Et, R3 — H A; R=Cl. OH, HNCOEt Both reactions gave the desired products 7 in com- in vitro against the Sarcoma 180 cells. The in vitro parable yields, however, compounds 7 prepared by results seemed to be encouraging [17]. However, the Todd-Atherton method seem to be of a better the lack of in vivo data, and difficulties which were quality, as evidenced by the fact that samples of 7 experienced in our laboratory in reproducing some prepared by the alternative method using diethyl of the results reported [17], prompted us to in- phosphorochloridate appeared to darken more ra- vestigate this class of compounds in greater detail. pidly on storage at 0 °C. Attempts to achieve the 886 G. Sosnovsky-J. Lukszo • In the Search for New Anticancer Drugs 886 Table I. Diethyl diaziridine -1-phosphonates 7 and diethyl-N1-benzylidene-N-methylhydrazinephosphonates 11. a 15 Com- Yield b.p. [°C/torr] Purity N25 Molecular M.S.: m/e I.R.e H NMR (CCl4)h pound [%] or m.p. [°C] [%] formula0 [M++l]d v [cm-1] ö [ppm] f 7a 38 74—79/0.04 1.4395 C10H23N2O3P 251 960, 1020, 1050, 0.93-1.51 (m, 18H), 250 1250, 2930 2.16-2.70 (m, 1H), 3.85-4.40 (m, 4H) 7c 69 79-81/0.12 94 1.4390 C8HI9N203P 223 970, 1030, 1260, 1.18 (t, 3H), (64) 76-78/0.10 96 1.4390 222 2980 1.35 (t, 6H), 1.61 (d, 3H), 2.23-2.75 (m, 2H), 2.83-3.48 (m, 1H), 3.91-4.50 (m, 4H) 7f 67 78-80/0.05 97 1.4393 C10H23N2O3P 251 950, 1010, 1040, 0.83-1.50 (m, 15H), 250 1240, 2950 1.55-2.11 (m, 3H), 2.53-3.10 (m, 1H), 3.73-4.33 (m, 4H) 7g 68 84-85/0.05 98 1.4405 C11H25N2O3P 265 960, 1020, 1250, 0.71-2.10 (m, 18H), (57) 88-89/0.07 93 1.4416 264 2920 2.36-2.78 (m, 2H), 2.81-3.56 (m, 1H), 3.78-4.38 (m, 4H) llh 44 50-51.5 C12H19N2O3P 271 970, 1010, 1140, 1.27 (t, 6H), 270 1250, 2950 3.16 (d, 3H), 3.66-4.30 (m, 4H), 7.03-7.58 (m, 6H) lli 30 94-95 Ci2Hi8ClN203Ps 305 960, 1010, 1140, 1.27 (t, 6H), 305 307 1250, 2950 3.16 (d, 3H), 3.66-4.30 (m, 4H), 7.03-7.58 (m, 5H) a Yields of products by Todd-Atherton method, except in ( ) which were obtained by using diethyl phosphoro- chloridate as described in the general procedure B; b by iodometric titration; c the microanalyses were in agreement with the calculated values: C ±0-36%, H ±0.21%, N ±0.40%; d chemical ionization applied; e compounds 7a, e, f and g analyzed neat, compounds 11 h and lli as KBr pellets; f no reaction with acidified solution of KI, in spite of confirmed diaziridine structure by 13CNMR; g for the chloroderivative lli, two characteristic peaks with intensity ratio of 3:1 was observed; h the appearance of dublets (3.16 ppm) for methyl protons [-N(CH3)-P] in 11 h and lli is attributed to phosphorus-hydrogen coupling. phosphorylation by the Todd-Atherton method for diaziridines derived from aromatic aldehydes. using an excess of a diaziridine as a hydrogen The reactions of Schiff bases 6 h and 6 i with hy- chloride acceptor failed, probably because of the droxylamine-O-sulfonic acid in the presence of a low basicity of diaziridines [37]. Products 7 were 40% aqueous methylamine solution following the purified by repeated vacuum distillations to con- literature procedure [34], for the preparation of 2h, stant boiling temperature at 0.04 to 0.12 torr.