TY - JOUR
T1 - Stereospecific mono- and difluorination of the C7-bridge of norbornenes
AU - Rajsfus, David E.
AU - Alter-Zilberfarb, Sari
AU - Sharon, Pessia
AU - Meador, Mary Ann B.
AU - Frimer, Aryeh A.
PY - 2011/5
Y1 - 2011/5
N2 - Fluorinated norbornenes are very desirable monomers in the semiconductor and high-temperature polyimide industries. We describe herein a synthetic strategy for the stereospecific mono- or difluorination of the C 7-carbon in norbornene systems beginning with 7-ketonadic anhydride 1. In particular, anti-7-fluoro methyl diester 4 and its 7,7-difluoronadic analog 7 can be prepared from 1 in 3 or 4 steps: saponification, reduction (for 4), esterification, fluorination with DAST. In addition, anti-7-fluoro-syn-7- fluoromethylnadic diester 16 is obtained from epoxide 14, and dimethyl 7,7-difluorobicyclo[2.2.2]oct-5-ene-2,3-dicarboxylate (17) from ketone 15. Anchimeric assistance of the norbornene double bond guides the introduction of attacking fluoride anions stereospecifically anti to the olefinic linkage.
AB - Fluorinated norbornenes are very desirable monomers in the semiconductor and high-temperature polyimide industries. We describe herein a synthetic strategy for the stereospecific mono- or difluorination of the C 7-carbon in norbornene systems beginning with 7-ketonadic anhydride 1. In particular, anti-7-fluoro methyl diester 4 and its 7,7-difluoronadic analog 7 can be prepared from 1 in 3 or 4 steps: saponification, reduction (for 4), esterification, fluorination with DAST. In addition, anti-7-fluoro-syn-7- fluoromethylnadic diester 16 is obtained from epoxide 14, and dimethyl 7,7-difluorobicyclo[2.2.2]oct-5-ene-2,3-dicarboxylate (17) from ketone 15. Anchimeric assistance of the norbornene double bond guides the introduction of attacking fluoride anions stereospecifically anti to the olefinic linkage.
KW - 7,7-Difluoronadic
KW - 7-Fluoronadic
KW - Anchimeric assistance
KW - Diethylaminosulfur trifluoride
KW - Stereospecific fluorination
UR - http://www.scopus.com/inward/record.url?scp=79955596906&partnerID=8YFLogxK
U2 - 10.1016/j.jfluchem.2011.03.009
DO - 10.1016/j.jfluchem.2011.03.009
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:79955596906
SN - 0022-1139
VL - 132
SP - 339
EP - 347
JO - Journal of Fluorine Chemistry
JF - Journal of Fluorine Chemistry
IS - 5
ER -