A small series of 2,2'-diselenobis(1H-indoles) was synthesized as redox-modified congeners of our earlier reported 2,2'-dithiobis(1H-indole) series. Utilizing chemistry similar to that developed earlier for the disulfur series, compounds were made from 2-halogeno-3-indolecarboxylic acid precursors bearing various polar functionality at the C-3 position and small alkyl substituents at the N-1 position of the indole nucleus. Additional compounds were derived from (R)- or (S)-tryptophan via a novel application of diselenium dichloride as an electrophilic source of diselenium, and a much improved process to a 2,2'-dithiobis(1H-indole) congener was developed utilizing disulfur dichloride as a source of disulfur. Against isolated epidermal growth factor receptor (EGFr), platelet-derived growth factor receptor (PDGFr), and v-src tyrosine kinases, compounds in this series displayed broad inhibitory activity with IC50 = 0.9 to > 100 microM vs EGFr, 3.4 to > 50 microM vs PDGFr, and 0.4-6.7 microM vs v-src. In general, compounds derived from tryptophan displayed the greatest potency against EGFr and those from 2-halogeno-3-indolecarboxylic acids greater potency against PDGFr and v-src. Enzyme kinetics studies showed that both classes of compounds display primarily noncompetitive inhibition with respect to either ATP or peptide substrate. The sulfhydryl reducing agent dithiothreitol (DTT) caused a general decrease in inhibition of the EGFr and v-src tyrosine kinases by both the diselenium and disulfur series with the reversal of enzyme inhibition occurring less readily within the diselenium series. In whole cell studies, compounds of this class were growth inhibitory against Swiss 3T3 mouse fibroblasts with IC50 values from 0.5 to 19.5 microM, and the observed SAR was different from that of the 2,2'-dithiobis(1H-indoles). A comparative study in the same cell line on the effects of the 2,2'-diselenobis(1H-indole) derived from (R)-tryptophan vs its disulfur congener on growth factor mediated tyrosine phosphorylation showed that this compound significantly inhibited EGFr and PDGFr (in response to its ligand) autophosphorylation with complete suppression at 25 and 5 microM, respectively. Tyrosine phosphorylation of an 85 kDa protein typically phosphorylated in response to bFGF was also exquisitely sensitive to this compound, and it displayed inhibitory effects on DNA, RNA, and protein synthesis at submicromolar concentrations. The disulfur congener exhibited a qualitatively similar pattern; however, its potency was 10-fold less. This same diselenium/disulfur pair was evaluated in vivo against the B16 melanoma, colon carcinoma 26, and M5076 sarcoma murine tumors, and the A431 epidermoid, and C6 glioma human tumor xenografts. At maximum tolerated doses (1.8 and 5.0 mg/kg/injection, respectively), neither the diselenium nor disulfur congener was effective against the C6 glioma when administered intraperitoneally on a d1-9 schedule. Studies were also carried out against the A431 epidermoid xenograft to evaluate the same pair of comp...

A practical process is described for the large-scale isolation of pentostatin, an adenosine deaminase inhibitor used clinically for the treatment of interferon-refractory hairy cell leukemia.The identities of minor components in the fermentation beer, including 2'-deoxyguanosine, are also reported.In 1969 the antiviral agent 9-(/?-D-arabinofuranosyl)adenine (Ara-A, vidarabine) was isolated from the fermentation beers of Streptomyces antibioticus1]. This "unnatural" adenine nucleoside is rapidly deaminated at C-6 by adenosine deaminase (ADA). Because of the large amount of Ara-A produced and the fact that ADAis commonlypresent in Streptomyces fermentation broths, chemists at Parke-Davis were prompted to search for an ADAinhibitor in S. antibioticus fermentation beers. These efforts were rewarded when a few milligrams of crystalline pentostatin (2'-deoxycoformycin) were isolated from several hundred liters of beer2). The structure of pentostain (1), CnH^N^O^was determined by chemical and spectroscopic techniques3) and is shown in Fig. 1. Subsequently, a total synthesis of 14) and selected analogs5) was reported. Because of its potent biological activity, the metabolism and biosynthesis of pentostatin have been extensively studied.6~9) Additionally, pentostatin labeled either with 3H or 14C has been prepared1°'1 1) for pharmacokinetic studies. Pentostatin is a powerful inhibitor of ADAand acts as a tight binding inhibitor of this enzyme12) with a Ki of 2.5 x 10~12 m. As expected, pentostatin greatly enhances the antiviral activity of Ara-A13). In later studies, pentostatin has been found to be effective against chronic lymphocytic leukemia14'1 5) and hairy cell leukemia.16'17) Indeed, pentostatin (Nipent) is now an approved and highly effective agent for the treatment of interferon-refractory hairy cell leukemia.18~20) To more fully evaluate pentostatin as an anticancer agent and to supply the large amounts needed for the clinic, an efficient process was required for its production.The major steps used for the original isolation of pentostatin involved a carbon adsorption/desorption procedure followed by chromatography on Darco G-60 and then on Sephadex G-102). The course of the fractionation was monitored by testing fractions for their ability to inhibit the deamination of adenosine by ADA.Repeated recrystallization of the product from the final, most active chromatographic fractions afforded less than 8 g of pentostatin from 9,500 liters of beer.The low yield and considerable labor involved in isolating pentostatin using this procedure were not practical for the production of kilogram lots of the drug. Therefore an alternative process, coupled with a rapid HPLCmethodfor assaying pentostatin, was developed. This report describes an efficient process (Scheme 1) for the large-scale isolation of pentostatin and the identification of four cometabolites. VOL. 45 NO. 12 THE JOURNAL OF ANTIBIOTICS 1915 Scheme1. Isolation of pentostatin. Filtration of the harvested fermentation beer, adjusted to pH 8.7 and cooled ov...

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Improved processes for the synthesis of bulk quantities of the anthrapyrazole clinical agents CI‐937, CI‐941, and piroxantrone hydrochloride are reported. Reported also are detailed analytical and spectroscopic data for these agents and intermediates of the synthetic sequences.

Improved processes for the synthesis of bulk quantities of the benzothiopyranoindazole clinical agent CI‐958 and A‐ring congeners is reported. The process chosen for scale‐up operations achieves β‐aminoethylation of an anilino precursor via a three‐step sequence (acylation, reduction, deprotection) starting from N‐(trityl)glycine. Detailed analytical data are reported for the target compounds and most intermediates, and detailed spectroscopy is given for CI‐958.