In this study, a series of N-(3-amino-1-oxo-2(1H)-isoquinolinyl)benzamides and butyramides were designed and synthesized, and several of them showed mitotic therapeutic activity against renal and breast tumors. The most effective compounds were N-(3-amino-1-oxo-2(1H)-isoquinolinyl)benzamides bearing an electron-withdrawing group on their benzamide moieties. N,N-Carbonyldiimidazole promotes cross-coupling between 2-(cyanomethyfibenzoic acids and commercial acyl hydrazides, followed by intra-molecular cyclization to afford these compounds via a two-stage protocol. This process is enhanced through addition of imidazole center dot HCl which serves as a catalyst for the production of the acyl imidazole/imidazolium intermediate through the first stage. Gentle overnight heating at 60 degrees C after the addition of the acyl hydrazide during the second stage affords a final product that either precipitates from the solution or forms as a pure compound upon addition of a small amount of water.

An alternative mild method for access to 1-aryl-3,3-dimethyl alkyl triazenes is described. This protocol employs the dropwise addition of a methanolic solution of a carboxylate (RCO2M) or carbonate (CO32−) to a gently heated DMF solution containing an aryl diazonium salt (ArN2+), that had been previously isolated. Presumably homolysis of the weak N–O bond of diazo ether adducts formed in this operation initiates radical pathways that lead to the generation of triazene product. DMF serves as not only a one-electron donor to the diazonium salts employed in this process, but also as a source of dimethylamine radicals that act as a nucleophilic coupling partner. The reaction provides modest yields (ca. 20–40%) across an array of aryl diazonium salts that contain various substitution. Furthermore this unique approach to triazenes contrasts with traditional methods that employ dimethyl amine in reagent form which directly couples with diazonium salts. Seemingly, only one other example employing somewhat similar reaction conditions to this current investigation en route to triazenes has been reported, albeit with lower yields and for one representative example furnished as a side-product. The current work here improves upon the efficiency of this reported result, and further expands the reaction scope.

The reaction of simple alkynoate salts with isolated arenediazonium tetrafluoroborate salts that had been pre-conditioned with the gold(I) catalyst AuCl(Me2S) led to the formation of cross-coupled products via a decarboxylative Sonogashira reaction process in modest yield and under mild conditions. The major by-product is a defunctionalized aryl moiety stemming from the diazonium salt, which competitively forms via hydrodediazonation. Good functional group tolerance and reaction site selectivity were attained in this limited investigation.

A functionally enriched ABCD ring system of podophyllotoxin was generated through Pd(II)-templated cyclization of an allcynoic alkene, prepared in five steps from commercially available 6-bromopiperonal. This research expands upon the recent carboesterification methodology of Dong et al. (Angew. Chem., Int. Ed. 2009, 48, 9690-9692) by the application of PdCl2(MeCN)(2), LiCl, and CuCl2 conditions, which yielded the desired podophyllotoxin scaffold with an embedded vinyl chloride moiety. Likewise, these conditions were successfully applied to a propargylic alkene prepared in three steps from 6-bromopiperonal. The resulting product contains the ABCD ring system of podophyllotoxin, but substitutes a D-ring furan for the D-ring lactone. Application of the recent methodology of Lu et al. (J. Org. Chem. 1995, 60, 1160-1169) on a related 1,6-enyne substrate led to functionalized alpha-methylene gamma-butyrolactones instead (Pd-2(dba)(3).CHCl3, LiBr, and CuBr2). The latter conditions applied to an alkynoic alkene afforded the ABCD ring system of podophyllotoxin with a vinyl bromide group. These vinyl halides allow for derivatization at a critical juncture in order to access novel podophyllotoxin analogs. (C) 2011 Elsevier Ltd. All rights reserved.

Despite being predicted to be stereoelectronically favorable by the Baldwin rules, efficient formation of a C-C bond through a 5-endo-dig radical cyclization remained unknown for more than 40 years. This work reports a remarkable increase in the efficiency of this process upon beta-Ts substitution, which led to the development of an expedient approach to densely functionalized cyclic 1,3-dienes. Good qualitative agreement between the increased efficiency and stereoselectivity for the 5-endo-dig cyclization of Ts-substituted vinyl radicals and the results of density functional theory analysis further confirms the utility of computational methods in the design of new radical processes. Although reactions of Br atoms generated through photochemical Ts-Br bond homolysis lead to the formation of cyclic dibromide side products, the yields of target bromosulfones in the photochemically induced reactions can be increased by recycling the dibromide byproduct into the target bromosulfones through a sequence of addition/elimination reactions at the exocyclic double bond. Discovery of a relatively efficient radical 5-endo-dig closure, accompanied by a C-C bond formation, provides further support to stereoelectronic considerations at the heart of the Baldwin rules and fills one of the last remaining gaps in the arsenal of radical cyclizations.

An enantioselective and diastereocontrolled approach to 8a-epi-d-swainsonine has been developed from achiral furfural. The key step to this synthesis was a one-pot procedure for the hydrogenolytic removal of two protecting groups and two intramolecular reductive amination reactions. The absolute stereochemistry was introduced by asymmetric Noyori reduction of furfuryl ketone. This route relies on diastereoselective palladium-catalyzed glycosylation to install the anomeric bond, and Luche reduction, diastereoselective dihydroxylation to set up the manno-stereochemistry of the indolizidine precursor.

Structure-based design and synthesis of the 3,4′-bispyridinylethylene series led to the discovery of 3-isoquinolinylpyridine 13a as a potent PKB/Akt inhibitor with an IC50 of 1.3nM against Akt1. Compound 13a shows excellent selectivity against distinct families of kinases such as tyrosine kinases and CAMK, and displays poor to marginal selectivity against closely related kinases in the AGC and CMGC families. Moreover, 13a demonstrates potent cellular activity comparable to staurosporine, with IC50 values of 0.42 and 0.59μM against MiaPaCa-2 and the Akt1 overexpressing FL5.12-Akt1, respectively. Inhibition of phosphorylation of the Akt downstream target GSK3 was also observed in FL5.12-Akt1 cells with an EC50 of 1.5μM. The X-ray structures of 12 and 13a in complex with PKA in the ATP-binding site were determined.

The selective oxidative conversion of a variety of highly functionalized 1°,2°-1,5-diols into the corresponding δ-lactones has been effected simply and efficiently using a reagent system comprised of catalytic 2,2,6,6-tetrmethylpiperidinooxy (TEMPO) and excess bis-acetoxyiodobenzene (BAIB).