title: Stereoselective synthesis of conjugated fluoro enynes.
abstract: Metalation-electrophilic fluorination of TMS- and TIPS-protected 1,3-benzothiazol-2-yl (BT) propargyl sulfones gave corresponding BT fluoropropargyl sulfones, Julia-Kocienski reagents for the synthesis of fluoro enynes. Both reagents reacted with aldehydes under mild DBU- or LHMDS-mediated conditions, giving high yields of conjugated fluoro enynes with E-stereoselectivity. In comparison to DBU-mediated reactions, stereoselectivity was higher in low-temperature LHMDS-mediated reactions. Two ketones were shown to react as well, using LHMDS as base. In situ removal of the TMS group gave terminal conjugated 2-fluoro 1,3-enynes. Synthetic utility of the fluoro enynes was demonstrated by conversion to internal alkynes and to stereoisomeric fluoro dienes via Sonogashira and Heck couplings.
authors.affiliation: Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, United States.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Barbara
authors.initials: B
authors.lastname: Zajc
mesh_terms: D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry*; D052160:Benzothiazoles / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D054879:Halogenation; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D052160:Benzothiazoles; D006845:Hydrocarbons, Fluorinated; D005461:Fluorine