514798-30-2Relevant academic research and scientific papers
Oxazaborolidinone-catalyzed enantioselective Diels-Alder reaction of acyclic α,β-unsaturated ketones
Singh, Ram Shanker,Adachi, Shinya,Tanaka, Fumi,Yamauchi, Toyonao,Inui, Chieko,Harada, Toshiro
, p. 212 - 218 (2008/09/18)
(Chemical Equation Presented) allo-Threonine-derived O-acyl-β-phenyl- oxazaborolidinones are demonstrated to be powerful and highly enantioselective Lewis acid catalysts for the Diels-Alder reaction of simple acyclic enone dienophiles, expanding the scope of ketone dienophiles and dienes. With 10 to 20 mol % of catalyst, the Diels-Alder adducts are obtained in 76-98% ee with high endo-selectivity. The catalyst exhibits high activity for the reaction with the less reactive β-substituted dienophiles and the less reactive 1,3-cycohexadiene and 1,3-butadiene derivatives. The application of the catalysts to the Diels-Alder reaction of furan is also described.
High facial selectivity observed in amine coordination to chiral oxazaborolidinones
Harada, Toshiro,Yamamoto, Yuuki,Kusukawa, Takahiro
, p. 859 - 861 (2007/10/03)
A variety of 1,3,2-oxazaborolidin-5-ones (OXB) derived from N-sulfonyl amino acids exhibit a high top-face selectivity in complexation with pyridines under thermodynamically controlled conditions. The Royal Society of Chemistry 2005.
Enantioselective Lewis Acid-Catalyzed Mukaiyama-Michael Reactions of Acyclic Enones. Catalysis by allo-Threonine-Derived Oxazaborolidinones
Wang, Xiaowei,Adachi, Shinya,Iwai, Hiroyoshi,Takatsuki, Hiroshi,Fujita, Katsuhiro,Kubo, Mikako,Oku, Akira,Harada, Toshiro
, p. 10046 - 10057 (2007/10/03)
allo-Threonine-derived O-aroyl-B-phenyl-N-tosyl-1,3,2 -oxazaborolidin-5-ones 1g,n catalyze the asymmetric Mukaiyama-Michael reaction of acyclic enones with a trimethylsilyl ketene S,O-acetal in high enantioselectivity. A range of alkenyl methyl ketones is successfully employed as Michael acceptors affording ee values of 85-90% by using 10 mol % of the catalyst. The use of 2,6-diisopropylphenol and tert-butyl methyl ether as additives is found to be essential to achieve high enantioselectivity in these reactions. The effects of the additives are discussed in terms of the retardation of an Si+-catalyzed racemic pathway, which seriously deteriorates the enantioselectivity of asymmetric Mukaiyama-Michael reactions. A working model for asymmetric induction is proposed based on correlation between catalyst structures and enantioselectivities.
Asymmetric Mukaiyama-Michael Addition of Acyclic Enones Catalyzed by allo-Threonine-Derived B-Aryloxazaborolidinones
Harada, Toshiro,Iwai, Hiroyoshi,Takatsuki, Hiroshi,Fujita, Katsuhiro,Kubo, Mikako,Oku, Akira
, p. 2101 - 2103 (2007/10/03)
(Formula Presented) O-(2-Naphthoyl)-N-tosyl-L-allo-threonine-derived B-phenyloxazaborolidinone catalyzes the asymmetric Mukaiyama-Michael addition of simple acyclic enones to give adducts of 54-85% ee. 2,6-Diisopropylphenol as an additive is demonstrated
