Recyclization reactions of 1-alkylpyrimidinium salts

The reaction of 4-amino-2-benzyl-1-methyl-5-ethoxycarbonylpyrimidinium iodide (3) with alcoholic methylamine resulted in the formation of the methylimine of 2-amino-4-hydroxy-6-methylamino-5-phenylpyridine-3-carbaldehyde (5). Heating of the same pyrimidinium salt in benzylamine gave a mixture of products of two C-C recyclizations: 2-benzyl-4-benzylamino-5-carbamoylpyrimidine (7) and the benzylimine of 4-amino-2-benzyl-6-benzylaminopyrimidine-5-carbaldehyde (8). The reaction of 2-amino-1,4-dimethyl-5-ethoxycarbonylpyrimidinium iodide (10) with KOH ethanolic solution gave a single product of C-C-recyclization: 2-amino-5-acetyl-4-hydroxypyrimidine (11).

(+)-agelasine D: improved synthesis and evaluation of antibacterial and cytotoxic activities

An improved synthesis of (+)-agelasine D (10) from (+)-manool is reported together with cytotoxic and antibacterial data for agelasine D and structurally close synthetic analogues. These compounds display a broad spectrum of antibacterial activities including effects on M. tuberculosis and Gram-positive and Gram-negative bacteria (both aerobes and anaerobes). They exhibit profound cytotoxic activity against several cancer cells, including a multidrug-resistant cell line. (+)-Agelasine D (10) has been isolated earlier from a marine sponge (Agelas sp.).

Synthesis and antimycobacterial activity of agelasine E and analogs

Agelasine E, previously isolated from the marine sponge Agelas nakamurai, has been synthesized for the first time, together with analogs with various terpenoid side chains. Treatment of N6-methoxy-9-methyl-9H-purin-6-amine with allylic bromides gave the desired 7,9-dialkylpurinium salts together with minor amounts of the N6-alkylated isomer. The N6-methoxy group was finally removed reductively. 1H-15N HMBC and 1H-15N HSQC NMR spectroscopy gave additional information on tautomerism and charge delocalization in the purine derivatives studied. The heterocyclic products were screened for activity against Mycobacterium tuberculosis and agelasine analogs carrying a relatively long terpenoid substituent in the purine 7-position and a methoxy group at N-6 were potent inhibitors of bacterial growth. Since agelasine analogs with the geranylgeranyl chain at N-7 exhibited antimicrobial activity, several strategies for synthesis of geometrically pure (2E,6E,10E)-geranylgeranyl bromide from geranyllinalool were evaluated.

Novel strategies for solid-phase construction of small-molecule combinatorial libraries

During the past decade we witnessed a rapid advance in the new field of chemical science, combinatorial chemistry. The pharmaceutical industries invested heavily in accelerating the development of this new technology. As a result, it has become an extremely important tool in lead identification and optimization in current pharmaceutical research. It also quickly crossed the boundaries of the original chemical discipline and demonstrated great potential in many other important areas, such as searching for novel and highly efficient catalysts and superconductive material. Researchers from both academic and industrial laboratories have directed great effort towards the development of novel strategies for combinatorial synthesis.