Synthesis and evaluation of 2,7-diamino-thiazolo[4,5-d] pyrimidine analogues as anti-tumor epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors.

2,7-Diamino-thiazolo[4,5-d]pyrimidine analogues were synthesized as novel epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. Representative compounds showed potent and selective EGFR inhibitory activities and inhibited in vitro cellular proliferation in EGFR-overexpressing human tumor cells. The synthesis and preliminary biological, physical, and pharmacokinetic evaluation of these thiazolopyrimidine compounds are reported.

Structure-based optimization of protein tyrosine phosphatase 1B inhibitors: from the active site to the second phosphotyrosine binding site.

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of the insulin and leptin receptor pathways and thus an attractive therapeutic target for diabetes and obesity. Starting with a high micromolar lead compound, structure-based optimization of novel PTP1B inhibitors by extension of the molecule from the enzyme active site into the second phosphotyrosine binding site is described. Medicinal chemistry, guided by X-ray complex structure and molecular modeling, has yielded low nanomolar PTP1B inhibitors in an efficient manner. Compounds from this chemical series were found to be actively transported into hepatocytes. This active uptake into target tissues could be one of the possible avenues to overcome the poor membrane permeability of PTP1B inhibitors.

An efficient direct amination of cyclic amides and cyclic ureas.

[reaction: see text] An efficient one-step amination of cyclic amides and ureas has been developed. Treatment of cyclic amides and cyclic ureas with BOP in the presence of DBU in various solvents led to the formation of cyclic amidines and cyclic guanidines in good to excellent yields. Concise syntheses of biologically intriguing kinetin and potent kinase inhibitor olomoucin were thus achieved in just one and two steps, respectively.

A highly facile and efficient one-step synthesis of N6-adenosine and N6-2'-deoxyadenosine derivatives.

[reaction: see text] A highly facile and efficient one-step synthesis of N6-adenosine and N6-2'-deoxyadenosine derivatives has been developed. Treatment of inosine or 2'-deoxyinosine, without protection of sugar hydroxyl groups, with alkyl or arylamines, in the presence of BOP and DIPEA in DMF, led to the formation of N6-adenosine and N6-2'-deoxyadenosine derivatives in good to excellent yields. Carcinogenic polyaromatic hydrocarbon (PAH) N6-2'-deoxyadenosine adduct 10 and a rare DNA constituent 11 were thus synthesized directly from 2'-deoxyinosine both in 98% yield.

Piperazine sulfonamides as potent, selective, and orally available 11beta-hydroxysteroid dehydrogenase type 1 inhibitors with efficacy in the rat cortisone-induced hyperinsulinemia model.

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is the enzyme that converts cortisone to cortisol. Evidence suggests that selective inhibition of 11beta-HSD1 could treat diabetes and metabolic syndrome. Presented herein are the synthesis, structure-activity relationship, and in vivo evaluation of piperazine sulfonamides as 11beta-HSD1 inhibitors. Through modification of our initial lead 5a, we have identified potent and selective 11beta-HSD1 inhibitors such as 13q and 13u with good pharmacokinetic properties.

Probing acid replacements of thiophene PTP1B inhibitors.

The following account describes our systematic effort to replace one of the carboxylate groups of our diacid thiophene PTP1B inhibitors. Active hits were validated using enzymatic assays before pursuing efforts to improve the potency. Only when the C2 carboxylic acid was replaced with another ionizable functional group was reversible and competitive inhibition retained. Use of a tetrazole ring or 1,2,5-thiadiazolidine-3-one-1,1-dioxide as a carboxylate mimetic led to the discovery of two unique starting series that showed improved permeability (PAMPA) and potency of the order of 300nM. The SAR from these efforts underscores some of the major challenges in developing small molecule inhibitors for PTP1B.

Stereoselective additions of chiral (E)-crotylsilanes to thionium ions: asymmetric synthesis of homoallylic thioethers.

Stereochemically well-defined homoallylic thioethers 3 are synthesized via Lewis acid promoted condensation reaction between chiral organosilane reagents 2 and in situ generated thionium ions. The stereochemical course of the reaction is consistent with earlier reports concerning crotylsilations of oxonium ions.