source_doi,diene,dienophile,solvent,temperature_c,time_h,concentration_m,endo_pct,exo_pct,isolated_yield_pct,method 10.1039/d0sc04553e,cyclopentadiene,methyl acrylate,benzene,80,6.5,1,77,23,86,quantitative 800 MHz 1H NMR