ChemInform Abstract: C‐Alkylation of the α‐Methylene Group in Deoxybenzoins

Synthetic model of a new deoxybenzoin derivative from Deguelia hatschbachii A.M.G. Azevedo

“…The MS and 13 C NMR spectral data of 2',4'dimethoxydeoxybenzoin [6] are now given for the first time.…”

“…The chemical investigation of the dichloromethane and petrol extracts from the roots of Deguelia hatschbachii A. M. G. Azevedo furnished a new deoxybenzoin derivative 1 (Figure 1); its structure was determined by spectral analysis (MS, 1 H and 13 C NMR) [1]. Previously only six natural deoxybenzoin 3a-3f derivatives have been isolated and five of these are a-methylated (Figure 2) [2][3][4][5][6][7][8].…”

“…The synthesis of a-methyl deoxybenzoins is achieved by methylation of deoxybenzoin derivatives [6]. In addition, deoxybenzoins are useful starting materials for the synthesis of several natural products, such as isoflavanones, stilbenes and others [9].…”

“…Moreover, it might be mentioned that the reactivity of deoxybenzoin derivatives with regard to a-alkylation remains little explored; and until now has been restricted to the a-methylation reaction [6,9].…”

Ruthenium-Catalyzed C–H Activation of Salicylaldehyde and Decarboxylative Coupling of Alkynoic Acids for the Selective Synthesis of Homoisoflavonoids and Flavones

“…The synthetic methods that have been reported thus far are categorized into three groups: (1) the cyclization of dihydrochalcone with one-carbon extension reagents such as Vilsmeier reagent, methanesulfonyl chloride/DMF, ethylformate/sodium, and DMF/2,4,6-trichloro-1,3,5-triazine; (2) the condensation of 4-chromanones with arylaldehydes, followed by rearrangement of the double bond via a base or rhodium; and (3) the cyclization of 1-( o -hydroxyphenyl)-1,3-diketone in the presence of anhydrides, strong acids, or bases . However, these methods have drawbacks with respect to the requisite multiple steps for the preparation of dihydrochalcone, 4-chromanone, and 1,3-diketone.…”