New anthracenyl-substituted phosphonates: Synthesis and utility

Abstract

Chlorination of α-hydroxyphosphonate anthracen-9-yl(5,5-dimethyl-2- oxo-2λ5-1,3,2-dioxaphosphinan-2-yl)methanol (11) using thionyl chloride unexpectedly yields 10-(5,5-dimethyl-2-oxo-2λ5-1,3, 2-dioxaphosphinan-2-ylmethylene)anthracen-9(10H)-one (13), 2-(10- chloroanthracen-9-ylmethyl)-5,5-dimethyl-2λ5-1,3, 2-dioxaphosphinan-2-one (14), and 10-(5,5-dimethyl-2-oxo-2λ5- 1,3,2-dioxaphosphinan-2-ylmethylene)-9,10-dihydroanthracen-9-ol (15) in addition to 2-[anthracen-9-yl(chloro)methyl]-5,5-dimethyl-2λ5-1,3,2- dioxaphosphinan-2-one (12). The reaction of 2-chloro-5,5-dimethyl-1,3,2- dioxaphosphinane (5) with 9-anthraldehyde leads to 2-chloro-1,1-dimethylethyl hydrogen 10-(5,5-dimethyl-2-oxo-2λ5-1,3,2-dioxaphosphinan-2- ylmethylene)-4a,9,9a, 10-tetrahydroanthracen-9-ylphosphonate (20) in addition to 12. Bromination of 11 with phosphorus tribromide affords the 10-bromoanthracen-9-yl product, 2-(10-bromoanthracen-9-ylmethyl)-5,5-dimethyl- 2λ5-1,3,2-dioxaphosphinan-2-one (22). Reaction of 12 with 4-chloro- or 4-nitrobenzaldehyde in the presence of sodium hydride affords the products, 9-(2-arylvinyl)anthracenes 23 and 24 in an uncommon Horner-Wadsworth-Emmons-type reaction. Compound 22 underwent the normal Horner-Wadsworth-Emmons reaction with benzaldehydes or ferrocenecarbaldehyde to afford disubstituted alkenes. One of these alkenes, (E)-9-bromo-10-[2-(4- bromophenyl)vinyl]anthracene (26), undergoes Sonogashira coupling with terminal alkynes to afford the conjugated alkynes (E)-9-bromo-10-[2-(4-ethynylphenyl) vinyl]anthracenes 30-32 in moderate yields. X-ray crystal structures of 12-15, 20, 23 and (E)-9-bromo-10-[2-(4-methoxyphenyl)vinyl]anthracene (27) have been determined. © Georg Thieme Verlag Stuttgart.