title: Synthesis of 3,4,5-Trisubstituted Isoxazoles from Morita-Baylis-Hillman Acetates by an NaNO2 /I2 -Mediated Domino Reaction.
abstract: An efficient NaNO2 /I2 -mediated one-pot transformation of Morita-Baylis-Hillman (MBH) acetates into alkyl 3-nitro-5-(aryl/alkyl)isoxazole-4-carboxylates is described. In a cascade event, initial Michael addition of NaNO2 to the MBH acetate furnishes the allylnitro intermediate which undergoes I2 -catalyzed oxidative α-CH nitration of the nitromethyl subunit followed by [3+2] cycloaddition to afford the title compounds. Structural elaborations of these highly substituted isoxazoles by SN Ar reactions and hydrogenolysis allows access to useful products.
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031 (India).
authors.forename: Shashikant U
authors.initials: SU
authors.lastname: Dighe
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031 (India).
authors.forename: Sushobhan
authors.initials: S
authors.lastname: Mukhopadhyay
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031 (India).
authors.forename: Shivalinga
authors.initials: S
authors.lastname: Kolle
authors.affiliation: Sophisticated Analytical Instrumentation Facility, CSIR, Central Drug Research Institute (India).|Academy of Scientific and Innovative Research, New Delhi (India).
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Kanojiya
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031 (India). batra_san@yahoo.co.uk, s_batra@cdri.res.in.|Academy of Scientific and Innovative Research, New Delhi (India). batra_san@yahoo.co.uk, s_batra@cdri.res.in.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Batra
mesh_terms: D000085:Acetates / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry*; D007555:Isoxazoles / Q000138:chemical synthesis*; D009566:Nitrates / Q000737:chemistry*
chemical_list: D000085:Acetates; D007555:Isoxazoles; D009566:Nitrates; C031618:sodium nitrate; D007455:Iodine
keywords: CH activation; Michael addition; cyclizations; heterocycles; iodine