Fluorene derivatives Halogen

The halogen-metal exchange reaction has been used almost exclusively for the formation of dithienylmethanes lithiated at thiophene /(-positions these derivatives give acceptable yields of aldehydes77 on reaction with dimethylformamide and of acids on carbonation.66 Particular use has been made of bis-J -lithiated compounds for the preparation (via oxidative coupling) of thiophene analogs of fluorenes.3,67 The synthesis of cyclopenta-[ 1,2-b 4,3-b]dithiophene (67) is typical (Eq. 23). 

The coupling of thienyl-lithium derivatives with cupric chloride to yield symmetrically substituted bithienyls has during recent years been extensively used in connection with work on optically active bithienyl derivatives and in connection with the synthesis of thiophen analogues of fluorene, " and dithienothiophens. " Thus 3,3 -bithienyl and 4,4 -dibromo-3,3 -bithienyl prepared in this way were brominated to form hexabromo-3,3 -bithienyl. Halogen-metal exchange occurred selectively in the 5,5 -positions, yielding the acid (93) upon carbonation. (93) was resolved into... 

The new advanced copolycarbonate resins are a copolymer of bisphenol A and bishydroxyphenol fluorene (BHPF), a fluorenyl derivate. Among the primary features of Inspire resins are equivalent or better heat and inherent ignition resistance without the use of halogens, improved processability, and superior transparency and optical properties when compared to advanced polymers. 

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