作者:W.Russell Bowman、Peter T. Stephenson、Adrian R. Young
DOI:10.1016/0040-4020(96)00636-9
日期:1996.8
Cascade radical reactions, initiated by cyclisation of sp3 carbon-centred radicals onto the C-atom of imines, have been used to develop a new protocol for the synthesis of a range of nitrogen heterocycles. The C-centred radical intermediates were generated from benzeneselenyl precursors using Bu3SnH. The aminyl radicals generated by cyclisation onto imines undergo further 5- or 6-exo cyclisation with
predominantly gave 6-endo cyclization products. These results suggest that the exo or endo selectivity of radicalcyclizationonto the alkenic bond of enamides can be controlled by positional change of the carbonyl group. For an understanding of these selectivities, heat of formation for each transition state was calculated. 6-endo-Selective radicalcyclization was applied to the radical cascade, enabling
synthesis of cyclicsulfinates and sulfinamides based on intramolecular homolyticsubstitution (SHi) at the sulfuratom by aryl or alkyl radicals is described. Both alkyl and benzofused compounds can be accessed directly from easily prepared acyclic precursors. Enantiomerically enriched sulfur‐based heterocycles were formed through an SHi process with inversion of configuration at the sulfuratom. Cyclization
描述了基于在硫原子上被芳基或烷基自由基的分子内均质取代(S H i)合成环状亚磺酸酯和亚磺酰胺的通用且有效的方法。烷基和苯并稠合的化合物都可以直接从容易制备的无环前体中获得。对映体富集的硫基杂环是通过S H i过程形成的,硫原子上的构型反转。前手性自由基的环化进行的立体化学结果各不相同,具体取决于传入自由基的大小。2-吡啶基和2-喹啉基会生成联芳基化合物,这是由于攻击芳基亚磺酸盐的邻位而不是亲硫取代引起的。
Radical cyclisations of imines and hydrazones
作者:W. Russell Bowman、Peter T. Stephenson、Nicholas K. Terrett、Adrian R. Young
DOI:10.1016/0040-4020(95)00412-2
日期:1995.7
Radical cyclisation of sp3 carbon-centred radicals onto imines and hydrazones provides a new method for the synthesis of 5- and 6-membered ring nitrogen heterocycles. Cyclisation onto the electrophilic carbon of the C=N group and 5-exo stereoelectronic selectivity are the dominating mechanistic parameters. The C-centred radical intermediates were generated from benzeneselenyl precursors using Bu3SnH
New complexes of functionalised ligands bearing P/N/Se or P2Se donor sets
作者:Sean E. Durran、Mark R. J. Elsegood、Martin B. Smith
DOI:10.1039/b204005k
日期:2002.9.23
[PdCl2(MeCN)2] affording an unusual trinuclear palladium(II) complex 7. Furthermore reaction of 3b with 1 equiv. of Ag[BF4] in dichloromethane gave the cationic complex [PtCl(1a)][BF4] 8 in which 1a functions as a P,N,Se-tridentate ligand. All structures have been confirmed by a combination of spectroscopic, analytical and single crystal X-ray studies. The structure of 8 represents, to the best of our knowledge