Asymmetric cycloaddition of anthrone with N-substituted maleimides with C2-chiral pyrrolidines

Aqueous ethanol: a suitable medium for the diastereoselective Diels–Alder reaction mediated by chiral bases

“…Overall, modest diastereoselectivity was observed for the reactions. We observed that only DielsÁAlder adducts as the major product were formed and we did not detect any Michael addition products as has been reported by Tokioka et al (43).…”

“…This diastereoselective DielsÁAlder reaction has been reported by some groups in organic solvents such as chloroform, dichloromethane (43). This polar reaction involving diene and dienophiles could be expected to exhibit rate enhancement in polar solvents.…”

Effective asymmetric Michael addition of anthrone to nitroalkenes using chiral tetraoxacalix[2]arene[2]triazines as organocatalysts

“…Anthrone generally serves as a reactive diene when a combination of an alkali and dienophiles is present, affording the necessary Diels–Alder adducts in high yields instead of the Michael addition adducts . It was reported that the Michael adducts were produced as side products in only a few cases in Diels–Alder reactions .…”

“…[8][9][10][11][12][13] Anthrone generally serves as a reactive diene when a combination of an alkali and dienophiles is present, affording the necessary Diels-Alder adducts in high yields instead of the Michael addition adducts. [14][15][16][17][18] It was reported that the Michael adducts were produced as side products in only a few cases in Diels-Alder reactions. 19,20 In contrast, nitroalkenes may be turned into a set of functionalities as reactive Michael acceptors because of the electron-withdrawing nitro group that is rarely utilized in the Diels-Alder reaction as a dienophile, despite a limited number of instances that have been shown by utilizing nitroalkenes as dienophiles in Diels-Alder reactions.…”

Absolute Configuration Determination and Convenient Asymmetric Synthesis ofcis‐3‐(9‐Anthryl)cyclohexanol with Proline as a Catalyst

“…Indeed, asymmetric [4 + 2] cycloadditions of 2 to N-substituted maleimides catalyzed by chiral Brönsted bases have been reported. [8][9][10] However, with a,b-unsaturated esters, ketones and nitro compounds conjugate addition of 2 is the preferred mode of reaction. 11,12 Asymmetric additions of 2 to a,b-unsaturated aldehydes catalyzed by a derivative of prolinol 13 and to enones using a thiourea derivative of 9-amino-9-deoxyepiquinine as a catalyst 14 have been recently disclosed.…”