A highly diastereoselective one-pot three-component 1,3-dipolar cycloaddition of cyclopropenes with azomethine ylides generated from 11H-indeno[1,2-b]-quinoxalin-11-ones (original) (raw)

2018, Organic chemistry frontiers

S2 1. Experimental data Table S1. Optimization of the reaction conditions a Entry Solvent T [°C] Time, h Yield 4aaa ,% b 1 methanol reflux 12 80 2 ethanol reflux 12 76 3 THF reflux 12 49 c 4 acetonitrile reflux 12 61 c 5 DMF 80 10 73 6 1,4-dioxane 80 12 43 c 7 DMSO 80 12 67 8 ethanol RT 72 54 c 9 methanol RT 72 51 c a Reaction conditions: 1a (1 equiv.), 2a (1 equiv.), 3a (2 equiv.), solvent. b Isolated yield. c Unreacted 1a and 2a are present in the reaction mixture. General procedure A for the one-pot three-component reaction of cyclopropenes, 11Hindeno[1,2-b]quinoxalin-11-ones, and secondary α-amino acids: A mixture of corresponding cyclopropene 1 (0.3 mmol), 11H-indeno[1,2-b]quinoxalin-11-one 2 (0.3 mmol), and secondary αamino acid 3 (0.6 mmol) was refluxed in methanol (6 mL) for 12 h until complete consumption of 1 as monitored by TLC. After cooling, the solvent was evaporated under reduced pressure. The residue was transferred into a separatory funnel using CH2Cl2 (5 mL), washed twice with water and brine. The washed organic phase was dried over anhydrous Na2SO4, filtered and concentrated on the rotary evaporator. The resulting crude product 4 was purified by recrystallization from MeOH or by preparative thin layer chromatography (PTLC) on alumina using a mixture of hexane-CH2Cl2 (2:1, 4haa, 4aac).