Synthesis of 3-hydroxycyclophosphamide and studies related to its possible role in the metabolism of cyclophosphamide

Abstract

Hydrogenolysis of 3-(benzyloxy)cyclophosphamide (10) using Pd/C catalyst and ethyl acetate as solvent leads to the formation of 3-hydroxycyclophosphamide (3, approximately 20%) and cyclophosphamide (1, approximately 10%), accompanied by regioselective hydrogen-exchange reactions at the C-4 and C-5 positions in 3 and 1. A variety of oxidizing reagents and liver microsomal incubation failed to provide evidence (31P NMR) for conversion of 1 into 3, whereas identical incubation of 3 led to its reduction to 1. Compound 3 is stable at pH 6.5-8.2, 37 degrees C, and exhibits anticancer activity comparable to 1 when tested against L1210 leukemia in mice. Data are discussed with regard to a previously reported suggestion that metabolism of 1 may involved oxidation to give 3 followed by rearrangement of 3 to 2.

Synthesis and Evaluation of 3-Halocyclophosphamides and Analogous Compounds as Novel Anticancer “Pro-Prodrugs”

“…The remaining solution was concentrated on a rotary evaporator, without heating'O, and the resultant oil was chromatographed on a column (2.2 cm X 25 cm) of silica gel using ethyl acetate as the eluent. Compound IV (Rf 0.5, ethyl acetate) was eluted with 85-135 ml of solvent and was obtained as a pale-yellow oil (252 mg, 20% yield); 31P-NMR (deuterium oxide): 6 3-Chlorocyclophosphamide (V)-A magnetically stirred solution of IeH20 (270 mg, 0.97 mmole) in chloroform (15 ml) was cooled with an ice-water bath, and an aqueous solution of sodium hypochlorite" [15 ml, 5.25% (w/w) NaOCI, 10.6 mmoles] was added; after 4 hr, the water bath was removed. Aliquots (1 ml) of the chloroform layer were periodically removed, diluted with deuterochloroform (1 ml), and the relative signal intensities for I(612.10) and the only detectable product (615.95) were measured by "P-NMR 5050.…”

“…The marked susceptibility of V and VI to reductive generation of I uia reaction with sulfhydryl-containing compounds led to the use of the fluoro derivative (IV) to assess the possibility of an enzyme-mediated reduction process formally analogous to that found for 111 and mouse liver microsomes (6). Due to the hydrolytic instability of IV, incubations were terminated after 10 min, during which time there was negligible hydrolysis to I.…”

“…Studies of such prodrugs by Zon et al (3)(4)(5)(6)(7)(8) have included labile precursors of the wellknown anticancer agent cyclophosphamide (I) (9). Since I functions as a prodrug (2, 9), these in uiuo precursors of cyclophosphamide may be viewed as "pro-prodrugs."…”

“…Since I functions as a prodrug (2, 9), these in uiuo precursors of cyclophosphamide may be viewed as "pro-prodrugs." For example, 3-(tert -butyldimethylsilyl)cyclophosphamide (11) can release I by spontaneous hydrolysis (5), and 3-hydroxycyclophosphamide (111) can afford I by reductive cleavage of the N-0 bond (6). While I1 proved to be inactive against L-1210 leukemia in mice (5), the in uiuo conversion of I11 to I was evidenced by comparable antileukemic activities for I11 and I in the L-1210 system and by the rapid formation of I on incubation of I11 with liver microsomes (6).…”