Sheng, Cheng; Ling, Zheng; Ahmad, Tanveer; Xie, Fang; Zhang, Wanbin published the artcile< Copper-Catalyzed Regioselective [3+3] Annulations of Alkynyl Ketimines with α-Cyano Ketones: the Synthesis of Polysubstituted 4H-Pyran Derivatives with a CF3-Containing Quaternary Center>, Application In Synthesis of 21667-62-9, the main research area is trifluoromethyl pyran preparation regioselective enantioselective; alkynyl ketimine cyano ketone ring closing reaction copper catalyst; [3+3] annulations; copper catalyzed; polysubstituted 4H-pyran derivatives.
Regioselective [3+3] annulation of alkynyl ketimines R1CCC(=NR)(CF3) (R1 = benzyl, naphthalen-1-yl, triethylsilyl, etc.; R = Boc) with α-cyano ketones R2C(O)CH2CN (R2 = Et, 4-methylphenyl, thiophen-2-yl, etc.) for the synthesis of polysubstituted 4H-pyran derivatives I with a quaternary CF3-containing center has been realized by using Cu(OAc)2 as the catalyst. The novel strategy tolerates a wide range of α-CF3 alkynyl ketimines and α-cyano ketones with both aryl and alkyl substituents. A preliminary asym. synthesis of chiral product II (R3 = Ph, 4-MeC6H4, 4-ClC6H4, etc.; R4 = Boc, Cbz) has been attempted by using copper and chiral thiourea as the cocatalyst with excellent yields (86-99%) and good enantioselectivities (71-78% ee). Furthermore, product I (R = Boc; R1 = R2 = Ph) could be obtained on a gram-scale reaction with 75% yield and 99% ee after recrystallization Several products were also transformed readily. Control experiments indicate that the reaction involves a process with a base-catalyzed or chiral thiourea-catalyzed Mannich-type reaction followed by a highly regioselective copper-catalyzed ring-closing reaction on the alkynyl moiety in a 6-endo-dig fashion.
Chemistry – A European Journal published new progress about [3+3] Cycloaddition reaction (regio-, stereoselective). 21667-62-9 belongs to class nitriles-buliding-blocks, and the molecular formula is C9H6ClNO, Application In Synthesis of 21667-62-9.
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts