BAKER - VENKATARAMAN Flavone synthesis

BAKER VENKATARAMAN Flavone synthesis Rearrangement of aromatic keto esters ot phenols to tiavones... 

BAKER - VENKATARAMAN Flavone synthesis Rearrangement 0/ aromatic keto esters ol phenols to Navones... 

BAER FISCHER Ammo sugar synthesis 10 BAEYER Oxindolesynthesis It BAEYER Oiarylmethane synthesis 11 BAEYER Pyridine synthesis 12 BAEYER - DREWSON Indoxyt synthesis 12 BAEYER VILLIGER Ketone oxidation 13 BAEYER - VILLIGER Tntylation 13 BAKER - VENKATARAMAN Flavone synthesis t4... 

Method 1 is a new method for the direct production of flavone from o-benzoyloxyacetophenone and has been successfully applied to the synthesis of other flavones. Method 2, which involves the Baker-Venkataraman transformation, is recommended because of its high over-all yield and the reproducibility of the results. Mozingo and Adkins method 8 is satisfactory but the yield of 0-hydroxydibenzoylmethane is variable. 

A facile Baker-Venkataraman synthesis of flavones (39), using PTC, has been recently proposed by Jain et al.66... 

The value of l-(o-hydroxyphenyl)-3-arylpropane-l,3-diones in the synthesis of O-heterocycles by the Baker-Venkataraman reaction with aroyl chlorides has been exemplified by their conversion into 3-acylflavones, flavones, flavanones and... 

The base-catalyzed rearrangement of aromatic ort/70-acyloxyketones to the corresponding aromatic (3-diketones is known as the Baker-Venkataraman rearrangement. 3-Diketones are important synthetic intermediates, and they are widely used for the synthesis of chromones, flavones, isoflavones, and coumarins. The most commonly used bases are the following KOH, potassium fert-butoxide in DMSO, Na metal in toluene, sodium or potassium hydride, pyridine, and triphenylmethylsodium. 

Song, G.-Y., Ahn, B.-Z. Synthesis of dibenzoylmethanes as intermediates for flavone synthesis by a modified Baker-Venkataraman rearrangement. Arch. Pharm. Res. 1994, 17, 434 37. 

Claisen condensation between an ester and the methylene adjacent to the carbonyl of the acylarene produces a l-(ortft(9-hydroxyaryl)-l,3-diketone. The Claisen condensation can be conducted in the presence of the acidic phenolic hydroxyl by the use of excess strong base triethylamine as solvent and base can also be utilised. " Alternatively, the process is conducted in two steps first, acylation of the phenolic hydroxyl, and secondly, an intramolecular ° base-catalysed Claisen condensation, known as the Baker-Venkataraman rearrangement a synthesis of flavone itself is illustrative. ... 

The Baker-Venkataraman rearrangement can be regarded as a 1,5-acyl migration in the enolate 12 and is of great value in the synthesis of flavones [36]. 

This reaction is closely related to the Baker-Venkataraman Rearrangement and Kostanecki-Robinson Reaction. Regarding the synthesis of flavone derivatives, the Allan-Robinson condensation is also related to the Algar-Flyn-Oyamada (AFO) Reaction and Auwers Synthesis. 

An alternative route to P-diketones 9 is the base-induced isomerization of (2-acyloxy)acetophenones 11 (Baker-Venkataraman rearrangement), which are readily obtained from O-acylation of (2-hydroxy)acetophenones. The Baker-Venkataraman rearrangement can be interpreted as a 1,5-acyl migration in the enolate 12 and is valuable for the synthesis of flavones [61] ... 

---