57677-67-5Relevant academic research and scientific papers
Rhodium(II)-catalyzed carbocyclization reaction of α-diazo carbonyls with tethered unsaturation
Padwa, Albert,Weingarten
, p. 3722 - 3732 (2007/10/03)
o-Alkynyl-substituted α-diazoketones undergo internal cyclization to produce indenone derivatives upon treatment with catalytic quantities of Rh(II)-carboxylates. A variety of structural influences were encountered by varying the nature of the substituent group attached to the diazo center. The cyclization reaction involves addition of a rhodium-stabilized carbenoid onto the acetylenic π-bond to generate a cycloalkenone carbenoid. The cyclized carbenoid was found to undergo both aromatic and aliphatic C-H insertion as well as cyclopropanation across a tethered π-bond. Subjection of diazo phenyl acetic acid 3-phenylprop-2-ynyl ester to Rh(II) catalysis furnished 8- phenyl-1,8-dihydro2-oxacyclopenta[a]indenone in high yield. The formation of this compound involves cyclization of the initially formed carbenoid onto the alkyne to produce a butenolide which then undergoes C-H insertion into the neighboring aromatic system. When a vinyl ether is added, the initially formed rhodium carbenoid intermediate can be intercepted by the electron-rich π-bond prior to cyclization. Different rhodium catalysts were shown to result in significant variation in the product ratios. The competition between bimolecular cyclopropanation, 1,2-hydrogen migration, and internal cyclization was probed using several enol ethers as well as diazoesters which possess different substituent groups on the ester backbone. The specific path followed was found to depend on electronic, steric, and conformational factors.
Furan-2(3H)- and -2(5H)-ones. Part 7. Photochemical behaviour of tetrahydro- and hexahydro-isobenzofuran-1-one systems: A mechanistic and exploratory study
Muraoka, Osamu,Tanabe, Genzoh,Igaki, Yuko
, p. 1669 - 1679 (2007/10/03)
The photoreactivity of two variations of the di-π-rnethane system involving the tetrahydro- and hexahydro-isobenzofuran structures 10 and 11 have been examined and compared with those of β-apolignans 1. The former, 9-phenyl-1,3,4,5,6,7,8,9-octahydronaphtho[2,3-c]furan-1-one 10a and 7-phenyl-1,3,4,7-tetrahydroisobenzofuran-1-one 10b, gave primarily the di-π-methane rearrangement products 18a and 18b, respectively, while the hexahydro substrate, 7-phenyl-1,3,4,5,6,7-hexahydroisobenzofuran-1-one 11, afforded mainly the photoreduced products 21-24. This difference in chemoselectivity is explained in terms of the variant configuration of the phenyl group, an axially orientated one migrating most effectively. A new pathway for the reaction leading to the cyclopropano product 18a or 18b, by way of another cyclopropano derivative 19a or 19b, respectively, is described.
REACTION OF 3a,4-DIHYDROPHTHALIDES WITH ACETYLENIC DIENOPHILES
Noguchi, Michihiko,Kakimoto, Shinji,Kajigaeshi, Shoji
, p. 665 - 668 (2007/10/02)
The tricycloocta-2,5-diene-4,7-carbolactones, the initially-formed Diels-Alder adducts from 3a,4-dihydrophthalides and acetylenic dienophiles, were so strained that they underwent the retro-Diels-Alder reaction to afford the benzene derivatives in good yields.
REGIOSELECTIVE SYNTHESIS OF SUBSTITUTED PHTHALIDES VIA INTRAMOLECULAR "DIENE-REGENERATIVE" DIELS-ALDER REACTION OF 2-PYRONES
Noguchi, Michihiko,Kakimoto, Shinji,Kawakami, Hisao,Kajigaeshi, Shoji
, p. 1085 - 1088 (2007/10/02)
Some 2-pyrone-6-carboxylates bearing appropriate dienophiles in ester moieties underwent "diene-regenerative" Diels-Alder reaction to afford the dihydrophthalides, which were aromatized to phthalide derivatives in the presence of palladium-charcoal.In these reactions the substituents at 4 or 7-position of phthalides arose from those on yhe dienophile moieties in the starting 2-pyrones.
