Imidazolidin-2-ones, chiral, Diels-Alder

Park, J., Sreekanth, P., and Kim, B. (2004) Recycling chiral imidazolidin-4-one catalyst for asymmetric Diels-Alder reactions ... 

Benaglia M, Celentano G, Cinquini M, Cozzi F, Puglisi A (2002) Poly(ethylene glycol)-supported chiral imidazolidin-4-one an efficient organic catalyst for the enantioselective diels-alder cycloaddition. Adv Synth Catal 344 149-152... 

Chiral secondary amines such as nonracemic imidazolidin-4-ones have been found to be effective asymmetric organocatalysts in the Diels-Alder cyclization of cyclopentadiene and a,p-unsaturated aldehydes [60]. A tyrosine-derived imidazoli-din-4-one was immobilized on PEG to provide a soluble, polymer-supported catalyst 110. In the presence of 110, Diels-Alder cycloaddition of acrolein 112 to 1,3-cyclohexadiene 111 proceeded smoothly to afford the corresponding cycloadduct 113 with high endo selectivity and enantioselectivity up to 92% ee (Scheme 3.31) [61]. 

MPEG with chiral imidazolidin-4-one =5,000" =0.2" CH3CN/H2O" En an tios elective Diels-Alder reactions Precipitation (diethyl ether) (r) [139]... 

The influence of solvents [64] and comparisons with catalysts of the diarylpro-linol series [65] were reported. For theoretical calculations on stereocontrol see Reference [66]. In addition, imidazolidin-4-one catalyzed cycloadditions have been used in several total syntheses of natural products. Intramolecular Diels-Alder reactions (IMDA) were reported as key steps in the synthesis of bicyclo-undecenes [67], amaminols [68], solanapyrones [69], telomerase inhibitor UCS1025A [70], englerin A [71], (-)-nor-platencin [72], and muironolide A [73]. In addition, asymmetric [3-1-2]-cycloadditions of azomethines were accomphshed in the presence of chiral imidazoUdinones [74]. Intermolecular cycloadditions of dihydropyridine 53 and acrolein catalyzed by imidazolidin-4-ones were reported. The chiral azabicyclo-octenol 54 was isolated as the important key intermediate in the total synthesis of lycopodium alkaloids [75] (e.g., ludduline) and oseltamivir (Scheme 4.19) [76]. 

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