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Aromatics to triquinanes. Synthesis and photoreaction of tricyclo[5.2.2.0(2,6)]undecanes having an alpha-methoxy beta,gamma-unsaturated carbonyl chromophore: A novel, efficient, and general route to linearly fused cis:anti:cis tricyclopentanoids

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Title Aromatics to triquinanes. Synthesis and photoreaction of tricyclo[5.2.2.0(2,6)]undecanes having an alpha-methoxy beta,gamma-unsaturated carbonyl chromophore: A novel, efficient, and general route to linearly fused cis:anti:cis tricyclopentanoids
 
Creator SINGH, V
THOMAS, B
 
Subject pi-methane photorearrangement
radical cyclization
natural-products
cyclo-additions
organic-synthesis
squarate esters
(+/-)-coriolin
photochemistry
rearrangement
construction
 
Description A novel, general, and stereoselective route for rapid creation of functionalized, linearly fused cis:anti:cis triquinanes from aromatic precursors has been presented. Cycloaddition of 2-methoxy-spiro[cyclohexa-2,4-diene-6-2'oxacyclopropan]one with various dienophiles and the photochemical reaction of appropriately designed tricyclic systems, having an alpha-methoxy beta,gamma-enone chromophore upon triplet (T-3) sensitization, are the key elements of our approach. A new and efficient methodology for the synthesis of endo-annulated bicyclo[2.2.2]octenones having an alpha-methoxy beta,gamma-enone chromophore (23-36) from o-vanillyl alcohol has been reported. The 2-methoxyspiro[cyclo-hexa-2,4-diene-6-2'-oxacyclopropan]one was generated by oxidation of o-vanillyl alcohol and trapped with cyclopentadiene (17), spiroheptadiene (18), and dimethylfulvene (19) to give the adducts 20-22 which were elaborated to a variety of chromophoric systems 23-36. The structure and stereochemistry of the tricyclic chromophoric systems (20-36) has been established through their high-field (300 MHz) H-1 NMR, C-13 NMR, and COSY spectra. Triplet-sensitized photochemical reaction of the chromophoric systems (23, 28-35) has been investigated. The triplet excitation of 28-34 led directly to the formation of functionalized triquinanes (43-48) in a single, stereoselective step. Interestingly, the irradiation of 23 furnished a novel tetracyclic product 40, whereas the irradiation of the substrate 35, having an additional alpha,beta-enone chromophore, gave a highly unusual pentacyclic product 55 as a result of participation of the OCH3 group in the photoreaction.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-13T17:25:46Z
2011-12-26T12:48:00Z
2011-12-27T05:42:58Z
2011-07-13T17:25:46Z
2011-12-26T12:48:00Z
2011-12-27T05:42:58Z
1997
 
Type Article
 
Identifier JOURNAL OF ORGANIC CHEMISTRY, 62(16), 5310-5320
0022-3263
http://dx.doi.org/10.1021/jo9702296
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3728
http://hdl.handle.net/10054/3728
 
Language en