To confirm the 1H and 13C NMR spectral assignments, HSQC spectrum was recorded for 5a and analyzed. The products were characterized on the basis of their IR, UV-visible, 1H NMR, 13C NMR and Mass spectral studies. Some 5,7-diaryl-3,4,6-trihydronaphthalen-2-ones were synthesized from 3,5-diarylcyclohex-2-en-1-ones and methyl vinyl ketone in the presence of sodium ethoxide. In this paper, we report synthesis of some 5,7-diaryl-3,4,6-trihydronaphthalen-2-ones. It can also be effected in onepot using acid catalysts16,17. Moreover, solvent-free Robinson annulation with sodium ethoxide15 was also performed. Robinson annulation can be performed under catalytic conditions using La(OiPr)3-MS 4A11, Al2O312, S-proline13, and AB38C214. It is an useful method for the synthesis of natural products consisting of fused ring systems such as terpenes and alkaloids10. A tandem reaction comprising a Michael addition step followed by an aldol condensation to produce a cyclic compound is Robinson annulation4-9. It is a versatile intermediate in the synthesis of various steroids and hormones.

There is a general interest in the synthesis of bicyclic ketone because this structural unit is the main function of various natural fragments. Michael reaction1 is the nucleophilic addition of a carbanion, formed from compounds containing active methylene group to an alpha-beta unsaturated ketone2, ester1, nitrile3, etc.

Diarly ketone synthesis