Asymmetric synthesis of rocaglamides via enantioselective photocycloaddition mediated by chiral brønsted acids

A method for preparing a compound with an aglain core structure, the method comprising steps of:

• producing an oxidopyrylium species (IT) by photoinduced excited state intramolecular proton transfer of a 3-hydroxychromone derivative (I);
• and
• reacting the oxidopyrylium species with a dipolarophile (IV) to obtain the aglain core-containing compound (V), wherein compounds (I), (IT), (IV) and (V) have the following chemical structures:
• wherein R1, R2, R3, R4, R, Ra and Rb are identical or different and selected from the group consisting of hydrogen, halogen, hydroxy, alkoxy, aryloxy, heteroalkoxy, heteroaryloxy, thioalkyl, thioaryl, acyl, aliphatic, alicyclic, heteroaliphatic, heterocyclic, aromatic, heteroaromatic, aryl, heteroaryl, alkylamino, amino alkyl, arylamino, amino aryl, a protecting group, —NO2, —CN, —CF3, —CH2CF3, —CHCl2, —CH2OH, —CH2CH2OH, —CH2SO2CH3, —C(═O)Rx, —CO2(Rx), —C(═O)N(Rx)2, —OC(═O)N(Rx)2, —OC(═O)Rx, —OCO2Rx, —S(O)Rx, —S(O)2Rx, —NRx(CO)Rx, —N(Rx)CO2Rx, —N(Rx)C(═O)N(Rx)2, —N(Rx)S(O)2Rx, and —S(O)2N(Rx)2,
• wherein each occurrence of Rx is independently selected from the group consisting of hydrogen, aliphatic, alicyclic, heteroaliphatic, heterocyclic, aromatic, heteroaromatic, aryl, and heteroaryl, and
• wherein the steps of producing the oxidopyrylium species and of reacting the oxidopyrylium species with a dipolarophile are carried out in the presence of a TADDOL derivative.

A method for preparing a compound with an aglain core structure, the method comprising steps of:

• producing an oxidopyrylium species (IIT) by photoinduced excited state intramolecular proton transfer of a 3-hydroxyflavone derivative (II);
• and
• reacting the oxidopyrylium species with a dipolarophile (IV) to obtain the aglain core-containing compound (V′), wherein compounds (II), (IIT), (IV) and (V′) have the following chemical structures:
• wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, Ra and Rb are identical or different and selected from the group consisting of hydrogen, halogen, hydroxy, alkoxy, aryloxy, heteroalkoxy, heteroaryloxy, thioalkyl, thioaryl, acyl, aliphatic, alicyclic, heteroaliphatic, heterocyclic, aromatic, heteroaromatic, aryl, heteroaryl, alkylamino, amino alkyl, arylamino, amino aryl, a protecting group, —NO2, —CN, —CF3, —CH2CF3, —CHCl2, —CH2OH, —CH2CH2OH, —CH2SO2CH3, —C(═O)Rx, —CO2(Rx), —C(═O)N(Rx)2, —OC(═O)N(Rx)2, —OC(═O)Rx, —OCO2Rx, —S(O)Rx, —S(O)2Rx, —NRx(CO)Rx, —N(Rx)CO2Rx, —N(Rx)C(═O)N(Rx)2, —N(Rx)S(O)2Rx, and —S(O)2N(Rx)2,
• wherein each occurrence of Rx is independently selected from the group consisting of hydrogen, aliphatic, alicyclic, heteroaliphatic, heterocyclic, aromatic, heteroaromatic, aryl, and heteroaryl, and
• wherein the steps of producing the oxidopyrylium species and reacting the oxidopyrylium species with a dipolarophile are carried out in the presence of a TADDOL derivative.