Synthesis of racemic and enantiomerically enriched α- oxyfunctionalized benzocyclanones and chromanones by dimethyldioxirane and dimethyldioxirane/Mn(III) salen system
Enolacetates of benzocyclanones and chromanones were synthesized and treated with dimethyldioxirane and the asymmetric oxidizing system dimethyldioxirane/chiral, non-racemic Mn(III) salen complex/axial ligand. The latter reagent resulted in the corresponding enantiomerically enriched cyclic α-hydroxy ketones and their acetates in moderate-to-good yields and modest enantioselectivity under mild and neutral conditions from tetralone and chromanone. On the contrary, flavanone provided poor yields due to the competitive C-H insertion at position 2. The use of R,R-Mn(III)salen catalyst induced an S absolute configuration at the position α in the whole series. Springer-Verlag 2004.
Patonay, Tamas,Jeko, Jozsef,Kiss-Szikszai, Attila,Levai, Albert
p. 743 - 756
(2007/10/03)
Hypervalent Iodine Oxidation of Flavanone. Synthesis of cis- and trans-3-Hydroxyflavanones
The synthesis of cis-3-hydroxyflavanone (3a) from flavanone (1) via acid-catalyzed hydrolysis of dimethyl acetal 4 formed by C6H5I(OAc)2-KOH/CH3OH oxidation is described.Unger more vigrous hydrolytic conditions isomerization accompanies hydrolysis of 4 wi
Moriarty, Robert M.,Prakash, Om
p. 151 - 153
(2007/10/02)
Lead Tetraacetate Oxidation of 4-Oximinoflavans
4-Oximinoflavans (I) give the corresponding flavanones (II), flavones (III), 3-acetoxyflavonols (IV) and 3-acetoxydihydroflavonols (V) on oxidation with lead tetraacetate in dry benzene.The yields of the major products, flavanones (II) range between 24 and 36percent.
Kale, Arun V.,Berge, Diwakar D.
p. 408 - 410
(2007/10/02)
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