Resin-bound 1,5,7-triazabicyclo[4.4.0]dec-5-enes were prepd. by copolymn. of 1,4-divinylbenzene and 4-vinylbenzyl chloride in the presence of either 2-ethylhexanoic acid, 1-chlorobutane, or cyclohexanol as a porogen followed by reaction with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD); the products were compared by IR and SEM, and their surface areas and pore sizes were detd. The resin-bound TBD were used as supported catalysts for the Michael addns. of 4-hydroxycoumarin to benzylideneacetones (E)-MeCOCH:CHR (R = Ph, 4-O2NC6H4, 4-ClC6H4, 4-MeOC6H4) in cyclopentyl Me ether to yield the (aryloxobutyl)hydroxycoumarins warfarin and three of its analogs I (R = Ph, 4-O2NC6H4, 4-ClC6H4, 4-MeOC6H4) in 82-100% conversions over 72-96 h; the catalysts were recovered by filtration and reused twice without loss of activity.
Synthesis and characterization of novel polystyrene-supported TBD catalysts and their use in the Michael addition for the synthesis of Warfarin and its analogues
ALONZI, MATTEO;BROGGI, Alessandra;LANARI, DANIELA;MARROCCHI, Assunta;VACCARO, Luigi
2014
Abstract
Resin-bound 1,5,7-triazabicyclo[4.4.0]dec-5-enes were prepd. by copolymn. of 1,4-divinylbenzene and 4-vinylbenzyl chloride in the presence of either 2-ethylhexanoic acid, 1-chlorobutane, or cyclohexanol as a porogen followed by reaction with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD); the products were compared by IR and SEM, and their surface areas and pore sizes were detd. The resin-bound TBD were used as supported catalysts for the Michael addns. of 4-hydroxycoumarin to benzylideneacetones (E)-MeCOCH:CHR (R = Ph, 4-O2NC6H4, 4-ClC6H4, 4-MeOC6H4) in cyclopentyl Me ether to yield the (aryloxobutyl)hydroxycoumarins warfarin and three of its analogs I (R = Ph, 4-O2NC6H4, 4-ClC6H4, 4-MeOC6H4) in 82-100% conversions over 72-96 h; the catalysts were recovered by filtration and reused twice without loss of activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
