Synthesis of the 2-chloro analogues of 3'-deoxyadenosine, 2',3'-dideoxyadenosine, and 2',3'-didehydro-2',3'-dideoxyadenosine as potential antiviral agents.

2-Chloro-3'-deoxyadenosine (2-chlorocordycepin), 2-chloro-2',3'-dideoxyadenosine (2-ClddAdo), and 2-chloro-2',3'-didehydro-2',3'-dideoxyadenosine (2-ClddeAdo) were synthesized from 2-chloroadenosine (2-ClAdo) as candidate antiretroviral agents on the basis that 2-chloro substitution would prevent enzymatic deamination and increase efficacy relative to 2',3'-dideoxyadenosine (ddAdo). Reduction of 2-chloro-5'-(4,4'-dimethoxytrityl)-2',3'-O-thiocarbonyladenosine with n-Bu3SnH, followed by detritylation with AcOH, unexpectedly gave a mixture of 2-chlorocordycepin and 2-chloroadenine. Treatment of the crude n-Bu3SnH reduction product with 1,1'-thiocarbonyldiimidazole, followed by another cycle of n-Bu3SnH reduction and detritylation with silica gel afforded 2-ClddAdo and a byproduct identified as 2-chloro-2',3'-O-methyleneadenosine.

4-Amino-3-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)-5-pyrazole-carb oni trile. Synthesis and conversion into a sugar-blocked 5,7-disubstituted formycin analog.

The title compound, a potential intermediate to protected C-nucleoside analogs related to formycin A, was synthesized via a new route wherein 2,3,5-tri-O-benzyl-1-O-p-nitrophenyl)-D-ribofuranose was converted to 2,5-anhydro-3,4,6-tri-O-benzyl-D-allonic acid, and further transformed into 4-(tert-butyloxycarbonyl)-5-ethoxycarbonyl-3-(2,3,5-tri-O-benzyl-beta-D- ribofuranosyl)pyrazole. After amidation and dehydration to form the 4-(tert-butyloxycarbonyl)-5-pyrazolecarbonitrile, acidolysis followed by a Curtius-type sequence afforded the 4-amino-5-pyrazole-carbonitrile nucleoside. Treatment of the latter with nitrous acid and copper chloride in a Sandmeyer-type reaction gave a diazonitrile rather than a chloronitrile.

Monensin is obligatory for the cytotoxic action of a disulfide linked methotrexate-anti-transferrin receptor conjugate.

Methotrexate (MTX) in the form of a gamma-cysteinylglycine derivative was disulfide linked to a monoclonal antibody reactive with the human transferrin receptor to give an antibody-MTX conjugate (anti-TfR-MTX). Antibody directed delivery of MTX to cell surface receptors was readily detected by flow cytometry using an anti-MTX antibody plus a secondary fluorescent antibody probe. Despite the presence of ample drug on the cell membrane, the conjugate alone was not cytotoxic over the course of several days.

Methotrexate analogues. 30. Dihydrofolate reductase inhibition and in vitro tumor cell growth inhibition by N epsilon-(haloacetyl)-L-lysine and N delta-(haloacetyl)-L-ornithine analogues and an acivicin analogue of methotrexate.

Analogues of methotrexate (MTX) with strong alkylating activity were prepared by replacing the L-glutamate side chain with N omega-haloacetyl derivatives of L-lysine and L-ornithine. Haloacetylation was accomplished in 30-40% yield by reaction of the preformed L-lysine and L-ornithine analogues of MTX with p-nitrophenyl bromoacetate or chloroacetate in aqueous sodium bicarbonate at room temperature. All four haloacetamides were potent inhibitors in spectrophotometric assays measuring noncovalent binding to purified dihydrofolate reductase (DHFR) from L1210 cells.

Synthesis and biologic activity of new side-chain-altered methotrexate and aminopterin analogs with dual inhibitory action against dihydrofolate reductase and folylpolyglutamate synthetase.

Replacement of the glutamic acid (Glu) moiety in methotrexate (MTX) and aminopterin (AMT) by 2-amino-4-phosphonobutyric acid (APBA) and ornithine (Orn) has been found to give analogs that retain the ability to inhibit dihydrofolate reductase (DHFR) while also displaying high activity against folylpolyglutamate synthetase (FPGS). One of these compounds, the Orn analog of AMT, is the most potent FPGS inhibitor we have found to date. A model to account for the fact that side-chain analogs containing a basic and those containing an acidic terminal group can both competitively inhibit FPGS is proposed.