Fig. 2: Synthesis of Pyrinap ligands and determination of rotation barrier between (R,Sa)-L2 and (R,Ra)-L2. | Nature Communications

Fig. 2: Synthesis of Pyrinap ligands and determination of rotation barrier between (R,Sa)-L2 and (R,Ra)-L2.

From: Pyrinap ligands for enantioselective syntheses of amines

Fig. 2

Reagents and conditions: (i) Pd(OAc)2 (5 mol%), PPh3 (20 mol%), Na2CO3 (2 equiv), DME/H2O = 3:1, reflux, (58%); (ii) (R)-1-phenylethyl amine or (R)-1-(1-naphthyl)ethyl amine (1.3 equiv), Pd(OAc)2 (5 mol%), rac-Binap (7.5 mol%), Cs2CO3 (1.4 equiv), toluene, reflux; (iii) HCl (3 M in MeOH/H2O), r.t.; (iv) PhNTf2 (1.0 equiv), Et3N (1.0 equiv), DMAP (10 mol%), DCM, r.t. (for Ar = Ph, 83% yield in step (ii) and 90% yield over 2 steps (iii and iv); for Ar = 1-naphthyl, 86% yield over 2 steps (ii and iii) and 90% yield in step (iv).) (v) NiCl2(dppe) (10 mol%), HPPh2 (2 equiv), DABCO (4 equiv), DMF, 120 °C, 12 h. DME 1,2-dimethoxyethane, DMAP 4-dimethylaminopyridine, DCM dichloromethane, DABCO triethylenediamine, DMF N,N-dimethylformamide.

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