Parallel Synthesis of a Desketoraloxifene Analogue Library via Iodocyclization/Palladium-Catalyzed Coupling
摘要:
For a future structure-activity relationship (SAR) study, a library of desketoraloxifene analogues has been prepared by parallel synthesis using iodocyclization and subsequent palladium-catalyzed coupling reactions. Points of desketoraloxifene diversification involve the two phenolic hydroxyl groups and the aliphatic amine side chain. This approach affords oxygen bearing 3-iodobenzo[b]thiophenes 4 in excellent yields, which are easily further elaborated using a two-step approach involving Suzuki-Miyaura and Mitsunobu coupling reactions to give multimethoxy-substituted desketoraloxifene analogues 6. Various hydroxyl-substituted desketoraloxifene analogues 7 were subsequently generated by demethylation with BBr(3).
Tolanes substituted in o-position by -SiHPh2, polymerize intermolecular with H2PtCl6/CH2Cl2 as catalyst, depolymerisation at 350–380 °C/1 torr yields the silaindenes.
A Novel Palladium-Mediated Coupling Approach to 2,3-Disubstituted Benzo[<i>b</i>]thiophenes and Its Application to the Synthesis of Tubulin Binding Agents
作者:Bernard L. Flynn、Pascal Verdier-Pinard、Ernest Hamel
DOI:10.1021/ol0067179
日期:2001.3.1
[GRAPHICS]Flexible, convergent access to 2,3-disubstituted benzo[b]thiophenes has been developed. The most concise approach involves sequential coupling of o-bromoiodobenzenes with benzylmercaptan and zinc acetylides to give benzyl o-ethynylphenyl sulfides which react with iodine to give 3-iodobenzo[b]thiophenes in a 5-endo-dig iodocyclization. These iodides can be further elaborated using palladium-mediated coupling and/or metalation techniques. This method has been applied to the synthesis of some novel tubulin binding agents.