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Studies on the catalytic hydrogenation of Baylis Hillman derivatives of substituted isoxazolecarbaldehydes

IR@CDRI: CSIR-Central Drug Research Institute, Lucknow


Field	Value

Creator	Saxena, Rashmi Singh, Vijay Batra, Sanjay

Date	2007-12-26T09:16:48Z 2007-12-26T09:16:48Z 2004

Identifier	Tetrahedron, 60, 10311 (2004) http://hdl.handle.net/123456789/44

Description	Results of the catalytic hydrogenation of Baylis-Hillman adducts obtained from substituted 3-, 4- and 5-isoxazolecarbox-aldehydes and their corresponding acetates in the presence of Raney-Ni and Pd-C are presented. The hydrogenation of Baylis-Hillman adducts of substituted 5-isoxazolecarbaldehydes and 3-isoxazolecarbaldehydes in the presence of Raney-Ni furnishes diastereoselectively syn enaminones over anti and in the presence of boric acid as an additive further enhancement of diastereoselectivity in favor of syn isomer is observed. The Pd-C-promoted hydrogenation of these substrates is also diastereoselective in favor of syn isomer but occurs without the hydrogenolysis of isoxazole-ring. The presence of boric acid as additive in this hydrogenation exhibits no pronounced effect on diastereoselectivity. The Raney-Ni-mediated hydrogenation of Baylis-Hillman adducts of substituted 4-isoxazolecarbaldehydes yield pyridone derivatives and Pd-C-promoted hydrogenation of the same substrate is diastereoselective to afford the anti isomer of the resulting products. The enaminones derived from Baylis-Hillman adducts of 3- and 5-isoxazolecarbaldehydes serve as versatile precursors for '-hydroxy-1, 3-diketones, which undergo acid-catalyzed ring-closure reaction to afford the furanone derivatives in excellent yields

Format	358552 bytes application/pdf

Language	en

Relation	CDRI Communication no. 6565

Subject	Baylis-Hillman isoxazolecarbaldehyde hydrogenation Raney-Ni Pd-C enaminones furanone

Title	Studies on the catalytic hydrogenation of Baylis Hillman derivatives of substituted isoxazolecarbaldehydes

Type	Article