Vinylogous Reactivity of Cyclic 2‐Enones: Organocatalysed Asymmetric Addition to 2‐Enals to Synthesize Fused Carbocycles

Abstract

Am ethod for asymmetric and site selective annulations at the g and g' positions of cyclic 2-enones with a,bunsaturated aldehydes has been developed. The organocatalysed [3+ +3]-annulations proceed with high levels of regio-, diastereo-, and enantioselectivity,a ffording as eries of high value fused carbocycles.Further elaboration gave key lactones (both bridged and fused).

Basicities and Nucleophilicities of Pyrrolidines and Imidazolidinones Used as Organocatalysts

“…Chiral pyrrolidines and imidazolidinones play a key role as organocatalysts in modern organic synthesis. − Numerous mechanistic investigations on organocatalytic transformations via intermediate enamines and iminium ions have been performed, mostly in water, DMSO, and acetonitrile. The rate of the initial step, commonly the nucleophilic attack of the secondary amine at the carbonyl group, depends on the nature of the carbonyl group as well as on the basicity and nucleophilicity of the amine.…”

Highly regioselective synthesis of lactamsviacascade reaction of α,β-unsaturated ketones, ketoamides, and DBU as a catalyst

“…36 Subsequently, regioselective Michael addition between b-substituted-cyclohexenones and nitroalkenes was explored. 32 In addition, some bifunctionalizations to obtain cycloadducts were reported by Chen and Jørgensen et al from the a ′ ,g-positions, 37 a ′ ,g ′ -positions, 23 b,g-positions, [38][39][40][41][42][43] g,g ′positions 44 and others [45][46][47] in cascade reaction of a,b-unsaturated ketones. In spite of many catalytic methodologies available for the functionalization of a,b-unsaturated ketones at their a, a ′ , b, g, g ′ positions and multiple reaction sites with a variety of substrates.…”