Design and synthesis of human immunodeficiency virus entry inhibitors: sulfonamide as an isostere for the alpha-ketoamide group.

The crystal structures of many tertiary alpha-ketoamides reveal an orthogonal arrangement of the two carbonyl groups. Based on the hypothesis that the alpha-ketoamide HIV attachment inhibitor BMS 806 (formally BMS378806, 26) might bind to its gp120 target via a similar conformation, we designed and synthesized a series of analogs in which the ketoamide group is replaced by an isosteric sulfonamide group. The most potent of these analogs, 14i, demonstrated antiviral potency comparable to 26 in the M33 pseudotyped antiviral assay. Flexible overlay calculations of a ketoamide inhibitor with a sulfonamide inhibitor revealed a single conformation of each that gave significantly better overlap of key pharmacophore features than other conformations and thus suggest a possible binding conformation for each class.

Heterobiaryl human immunodeficiency virus entry inhibitors.

Previously disclosed HIV (human immunodeficiency virus) attachment inhibitors, exemplified by BMS 806 (formally BMS378806, 1), are characterized by a substituted indole or azaindole ring linked to a benzoylpiperazine via a ketoamide or sulfonamide group. In the present report, we describe the discovery of a novel series of potent HIV entry inhibitors in which the indole or azaindole ring of previous inhibitors is replaced by a heterobiaryl group. Several of these analogues exhibited IC(50) values of less than 5 nM in a pseudotyped antiviral assay, and compound 13k was demonstrated to exhibit potency and selectivity similar to those of 1 against a panel of clinical viral isolates. Moreover, current structure-activity relationship studies of these novel biaryl gp120 inhibitors revealed that around the biaryl, a fine crevice might exist in the gp120 binding site. Taken in sum, these data reveal a hitherto unsuspected flexibility in the structure-activity relationships for these inhibitors and suggest new avenues for exploration and gp120 inhibitor design.

Synthesis and characterization of novel monocarbollide exo-closo-(pi-arene)biruthenacarboranes [(PPh3)mClRu(eta6-C6H5R)Ru'CB10H11-n(OMe)n] (where R = H, m = 2, n = 1; R = mu-PPh2, m = 1, n = 0, 1).

The monocarbon carborane [Cs][nido-7-CB(10)H(13)] reacts with the 16-electron [RuCl(2)(PPh(3))(3)] in a solution of benzene/methanol in the presence of N,N,N',N'-tetramethylnaphthalene-1,8-diamine as the base to give a series of 12-vertex monocarbon arene-biruthenacarborane complexes of two types: [closo-2-[7,11-exo-RuClPPh(3)(mu,eta(6)-C(6)H(5)PPh(2))]-7,11-(mu-H)(2)-2,1-RuCB(10)H(8)R] (5, R = H; 6, R = 6-MeO; 7, R = 3-MeO) and [closo-2-(eta(6)-C(6)H(6))-10,11,12-[exo-RuCl(PPh(3))(2)]-10,11,12-(mu-H)(3)-2,1-RuCB(10)H(7)R(1)] (8a, R(1) = 6-MeO; 8b, R(1) = 3-MeO, inseparable mixture of isomers) along with trace amounts of 10-vertex mononuclear hypercloso/isocloso-type complexes [2,2-(PPh(3))(2)-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(7)] (9) and [2,5-(Ph(3)P)-2-Cl-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(6)] (10). Binuclear ruthenacarborane clusters of both series were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of three selected complexes, 6-8. In solution, isomers 8a,b have been shown to undergo the isomerization process through the scrambling of the exo-[RuCl(PPh(3))(2)] fragment about two adjacent triangular cage boron faces B(7)B(11)B(12) and B(8)B(9)B(12).