Domino carbonylation

Scheme 1.16. Indium(lll)-catalyzed domino carbonyl-ene reaction...

The domino carbonylation and Diels-Alder reaction proceed only as an intramolecular version. Attempted carbonylation and intermolecular Diels-Alder reaction of conjugated 2-yne-4-enyl carbonates 101 in the presence of various alkenes as dienophiles give entirely different carbocyclization products without undergoing the intermolecular Diels-Alder reaction. The 5-alkylidene-2-cyclopenten-4-onecarboxy-lates 102 were obtained unexpectedly by the incorporation of two molecules of CO in 82% yield from 101 at 50 °C under 1 atm [25], The use of bidentate ligands such as DPPP or DPPE is important. The following mechanism of the carbocyclization of 103 has been proposed. The formation of palladacyclopentene 105 from 104 (oxidative cyclization) is proposed as an intermediate of 108. Then CO insertion to the palladacycle 105 generates acylpalladium 106. Subsequent reductive elimination affords the cyclopentenone 107, which isomerizes to the cyclopentenone 108 as the final product. 

Scheme 1133 Domino carbonylation and ene reaction to afford the cyclohexadiene ring.

Domino Carbonylation and Diels-Alder reaction (Scheme 11-31) [29]... 

Scheme 11.31 Domino carbonylation and Diels-Alder reaction.

Hashimoto has reported the enantioselective domino carbonyl yUde formation/l,3-dipolar cycloaddition reaction of a range of a-diazo ketones 185 with various aromatic aldehydes 92, promoted by the chiral Rh(II)-tetrakis[N-benzene-fused-phthaloyl-(S)-valinate] complex (184). The present reaction afforded the corresponding bicyclic cycloadducts 186 in good yields and enantioselectivities. The exo diastereomer 186 was diastereoselectively generated as a single product in almost all the cases (Scheme 11.40) [61]. 

Scheme 11.40 Chiral Rh2(N)-catalyzed domino carbonyl ylide formation/l,3-dipolar cycloaddition [51].

Scheme 11.42 Intramolecular domino carbonyl ylide formation/1,3-dipolar cycloaddition [53].

Scheme 7.52 Domino carbonyl ylide formation-enantioselective reduction reaction catalysed by chiral phosphoric acid catalysis and rhodium catalysis followed by benzoylation.

Hashimoto and coworkers accomplished the immobilization of chiral dirhodium (II) catalyst on a polystyrene-based copolymer. The polymer catalyst (55), which was packed in a gravity fed column, was successfully applied in a domino carbonyl ylide formation - dipolar cydoaddition under continuous-flow conditions (Scheme 7.39). The desired bicyclic adduct was obtained in high yield and high levels of asymmetric induction (up to 99% ee). The flow reactor was demonstrated by the retention of activity and enantioselectivity even after 60 h with a low metal leaching level (2.1 ppm) [146]. 

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