Stereochemical and mechanistic aspects of dioxygenase-catalysed benzylic hydroxylation of indene and chromane substrates
作者:Derek R. Boyd、Narain D. Sharma、Nigel I. Bowers、Rosemary Boyle、John S. Harrison、Kyoung Lee、Timothy D. H. Bugg、David T. Gibson
DOI:10.1039/b300898c
日期:2003.4.14
Toluene dioxygenase (TDO)-catalysed benzylic hydroxylation of indene substrates (8, 16 and 17), using whole cell cultures of Pseudomonas putida UV4, was found to yield inden-1-ol (14 and 22) and indan-1-one bioproducts (15 and 23). The formation of these bioproducts is consistent with the involvement of carbon-centred radical intermediates. TDO-catalysed oxidation of indenes 8 and 16 also gave cis-diols 13 and 18 respectively. TDO and naphthalene dioxygenase (NDO), used as both whole-cell preparations and as purified enzymes, were found to catalyse the benzylic hydroxylation of chromane 30, deuteriated (±)-chromane 30DDDDDDD and enantiomers (4S)-30DDDDDDD and (4R)-30DDDDDDD to yield (4R)- and (4S)-chroman-4-ols 31/31DDDDDD respectively. The mechanism of benzylic hydroxylation of chromane 30/30DDDDDDD involves the stereoselective abstraction of a pro-R
(with TDO) or a pro-S
(with NDO) hydrogen atom at C-4 and a marked preference for retention of configuration.
different steric requirements under refluxing benzene afforded a single stereoisomer of the cyclopropane derivatives 4. The same reaction under refluxing ethanol gave the normal products, i.e. the trans-lactones 6. Mechanism and high stereoselectivity observed in the novel cyelopropane formation, and regiospecific cleavage of the cyclopropane carboxylic acids (in4) have also been discussed in detail
A successful synthesis of pterocarpans 1, based on a "disfavored" 5-endo-trig radical cyclization reaction, has been accomplished. The radical precursor 4-(2'-bromoaryloxy)-2H-chromene 8 was synthesized in six steps, starting from aryl propynyl ether 2. On treatment with tributyltin hydride in refluxing benzene, aryl enol ether 8 underwent radical cyclization to furnish the pterocarpan 1. A deuterium
Processes for preparing optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compounds and intermediates therefor
申请人:YOSHITOMI PHARMACEUTICAL INDUSTRIES, LTD.
公开号:EP0386640A2
公开(公告)日:1990-09-12
The present invention provides an industrially valuable method for preparing optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compounds which are useful as a starting material for optically active benzopyran compounds with antihypertensive, coronary blood flow-increasing activities and the like, and also provides diastereomeric ester compounds with a 3-halo-4-hydroxy-2H-1-benzopyran compound which are useful as an intermediate for said epoxy compounds.
Method for preparing optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compounds, intermediates therefor and uses thereof
申请人:YOSHITOMI PHARMACEUTICAL INDUSTRIES, LTD.
公开号:EP0456266A1
公开(公告)日:1991-11-13
The present invention provides an industrially valuable method for preparing an optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compound which is useful as a starting material for an optically active benzopyran compound with antihypertensive, coronary blood flow-increasing activities and the like, provides a diastereomeric ester compound which is useful as an intermediate for said epoxy compound and also provides a use of said diastereomeric ester compound in making of said epoxy compound, and further an optically active benzopyran compound which is useful as medicine.