Control of the Regio- and Diastereoselectivity for the Preparation of Highly Functionalized Terpenic Cyclopentanes through Radical Cyclization
作者:Jesús F. Arteaga、Horacio R. Diéguez、José A. González-Delgado、José F. Quílez del Moral、Alejandro F. Barrero
DOI:10.1002/ejoc.201100400
日期:2011.9
The titanocene-mediated cyclization of suitably functionalized acyclic C10 epoxy-polyprenes leads, with moderate stereoselectivity, to high yields of functionalized terpenic cyclopentanes with three contiguous stereogenic centers. These highly functionalized cyclopentanes are useful intermediates for the synthesis of several natural compounds that include this interesting subunit in their structure
The synthesis of the diterpene (+)-tonantzitlolone A and a series of derivatives is reported. The study includes the determination of their antiproliferativeactivities against selected cancer cell lines.
Soluble and matrix-bound P450 enzyme models have been synthesized carrying a SO3 - ligand coordinating to iron. These complexes display features very similar to cofactors of enzymes such as P450cam with respect to electrochemistry and UV/Vis spectroscopy. Further they catalyze epoxidation reactions with turnover numbers up to 1800. DFT calculations revealed that the coordination of SO3 - to Fe(III) produces an active species that displays allylic hydroxylation and epoxidation reactivity patterns that are nearly indistinguishable from those calculated for the natural active species of the enzyme cytochrome P450.
α-ketene alkyl and α,β-unsaturated acyl radical intermediates in ring constructions
作者:Christopher J Hayes、Gerald Pattenden
DOI:10.1016/0040-4039(95)02147-7
日期:1996.1
Treatment of the E-α,β-unsaturated selenyl esters 1 and 3a with Bu3SnH-AIBN produces the corresponding cyclohexenones 2 and respectively via presumed α-ketenealkylradicalintermediates. In a similar manner the cyclopropyl ester 9 leads to a mixture of 12 and 13, and the 2,7-diene selenyl ester 15 undergoes a novel bi-cyclisation producing the diquinane 17 in 76% yield.
α,β-Unsaturated and cyclopropyl acyl radicals, and their ketene alkyl radical equivalents. Ring synthesis and tandem cyclisation reactions
作者:Christopher J. Hayes、Nicola M. A. Herbert、Nicole M. Harrington-Frost、Gerald Pattenden
DOI:10.1039/b413815p
日期:——
25a on treatment with Bu(3)SnH-AIBN. Furthermore, in the presence of methanol the only product from this reaction was the bis(methyl ester) dimer 25b, thereby lending further credence to the involvement of ketene alkyl radical intermediates in these reactions, and in the aforementioned reactions involving 2,6- and 2,7-diene selenyl esters. Treatment of the cyclopropane selenyl esters and , containing