Reactions of α-alkyl- or α-halogeno-alkoxycarbonylmethylene(triphenyl)phosphoranes with phenanthrene-9, 10-quinone. Synthesis of phenanthro[9, 10-b]furan derivatives

Syntheses of chromenes and chromanes via o‐quinone methide intermediates

“…The authors found that their stabilities were dependent on the electronegativity and bulkiness of the substituents on the o ‐QM moiety. Later on, Nicolaides et al [135] revisited the reaction and prepared other o ‐QMs ( e.g. , 18 ) (Scheme ).…”

Reactions of α-Diketones ando-Quinones with Phosphorus Compounds

“…α-Ethylethoxycarbonylmethylene(triphenyl)phosphorane ( 222 , R = Et) reacts with o -quinone 215 to form furan derivative 221 with compound 223 . On the other hand, the reaction of ylide 222 (R = CH 2 Ph) with the same quinone affords phenanthro[9,10- b ]furan derivatives 224 and 225 , respectively …”