Synthesis of 2,3,5,6-tetrahydro-1-alkyl/aryl-1H-benzo[f]chromen-3-ol derivatives from ß-tetralones and α,ß-unsaturated aldehydes.

Organocatalytic domino Michael-hemiacetalization of ß-tetralones with α,ß-unsaturated aldehydes is presented. Treatment of ß-tetralones with α,ß-unsaturated aldehydes in the presence of diphenylprolinol silyl ether gave 2,3,5,6-tetrahydro-1-alkyl/aryl-1H-benzo[f]chromen-3-ol derivatives with high to excellent chemical yields (50-99%) and high levels of enantioselectivities (up to 96% ee).

Pyrrolidinyl-camphor derivatives as a new class of organocatalyst for direct asymmetric Michael addition of aldehydes and ketones to beta-nitroalkenes.

Practical and convenient synthetic routes have been developed for the synthesis of a new class of pyrrolidinyl-camphor derivatives (7 a-h). These novel compounds were screened as catalysts for the direct Michael addition of symmetrical alpha,alpha-disubstituted aldehydes to beta-nitroalkenes. When this asymmetric transformation was catalyzed by organocatalyst 7 f, the desired Michael adducts were obtained in high chemical yields, with high to excellent stereoselectivities (up to 98:2 diastereomeric ratio (d.r.) and 99 % enantiomeric excess (ee)). The scope of the catalytic system was expanded to encompass various aldehydes and ketones as the donor sources. The synthetic application was demonstrated by the synthesis of a tetrasubstituted-cyclohexane derivative from (S)-citronellal, with high stereoselectivity.