Nucleophilic and electrophilic substitutions of difluoropropargyl bromides
作者:Gerald B. Hammond
DOI:10.1016/j.jfluchem.2005.12.024
日期:2006.5
electrophilically substituted difluoropropargyl derivatives via magnesium and fluoride promoted reactions. An indium-mediated reaction of silyldifluoropropargyl bromide, followed by electrophilic trapping with bromine led to a very useful bromoallene, which was then used in reactions with nucleophiles (C, O, N, P, S, Hal) to yield a de facto bimolecular nucleophilic substitution of a difluoropropargyl
An integrated fully differential CMOS transimpedance amplifier (TIA) with buried double junction photodiode input is described. The TIA features a variable high transimpedance gain (250 kΩ to 2.5 MΩ), large DC photocurrent rejection capability (>55 dB) and low input referred noise density at 100 kHz (2pA/√Hz).
Highly Regioselective Synthesis of <i>gem</i>-Difluoroallenes through Magnesium Organocuprate S<sub>N</sub>2‘ Substitution
作者:Masayuki Mae、Jiyoung A. Hong、Bo Xu、Gerald B. Hammond
DOI:10.1021/ol052816g
日期:2006.2.1
[GRAPHICS]The reaction of gem-difluoropropargyl electrophiles with Grignard reagents is complicated by the inherent difficulty of executing nucleophilic substitutions on a CF2 group, and the facile formation of carbenoid intermediates arising from alpha-elimination of fluoride. In the presence of an excess amount of a copper salt, a Grignard reagent reacts with gem-difluoropropargyl bromide via an SINT mechanism to produce gem-difluoroallene in high yield. If desired, the resulting difluoroallene can undergo a second nucleophilic attack on the CF2 terminus to yield a trisubstituted monofluoroallene through an addition-elimination mechanism.
Crystallographic Characterization of Difluoropropargyl Indium Bromide, a Reactive Fluoroorganometallic Reagent