Synthesis of Diaryl-a-tetralones

Tab. 5.31 Synthesis of diaryl-a-tetralones from isophorone and chalcone under MW + PTC conditions.

One-pot synthesis of diaryl-a-tetralones via Michael condensation and subsequent Robinson annulation reactions of isophorone with chalcones was performed efficiently in a solvent-free PTC system under the action of MW irradiation. Compared with conventional heating, substantial rate enhancements were observed, within very short reaction times, by use of microwaves (Eq. (76), Table 6.34). They were far better than those achieved by the classical method (NaOEt in EtOH under reflux for 24 h 40-56%). 

Quallich and Woodall described the first asymmetric synthesis utilizing a catalytic enantioselective reduction of the ketoester 35 with (S)-terahydro-l-methyl-3,3-diphenyl-lH,3W-pyrrolo[l,2-c][l,3.2]oxazaborole (CBS) to give the desired hydroxyester 36 (90% ee). After mesylation, Sn2 displacement with a higher-order cuprate derived from copper cyanide gave the diaryl r-butyl ester 37 with good chirality transfer. Intramolecular Friedel-Crafts cyclization gave the tetralone 31 in 90% ee (Scheme 7). ... 

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