Preparation of α-functionalized alkenylmagnesium reagents via a halide–magnesium exchange

Highly Functionalized Organomagnesium Reagents Prepared through Halogen–Metal Exchange

“…After transmetallation with ZnBr 2 , 188 undergoes a smooth Negishi cross-coupling with 3-iodo-2-methyl-cyclohex-2-enone (28), leading to the enone 189 in 55 % yield (Scheme 34). [88,89] The preparation of related carbonyl-containing alkenyl magnesium reagents was reported by Hiemstra and co-workers in the course of synthetic studies toward the synthesis of solanoeclepin A. [90,91] Treatment of the cyclic alkenyl iodide 190 with iPrMgCl in THF at À78 8C furnished the desired Grignard reagent 191, which reacts with acrolein and catalytic CuBr·Me 2 S in THF/HMPA in the presence of TMSCl to furnish the Michael adduct 192 in 89 % yield (Scheme 35).…”

An α-Diaminoboryl Carbanion Assisted Stereoselective Single-Pot Preparation of α,β-Disubstituted Acrylonitriles

“…This product spectroscopically matched that of the known compound. 16 133.7 132.4, 129.5, 129.0, 128.7, 120.2, 118.2, 113.0, 33.9; HRMS (TOF MS ES + ) calcd for C 12 H 11 NNa 192.0789 [M + Na] + , found 192.0786.…”

A torquoselective extrusion of isoxazoline N-oxides. Application to the synthesis of aryl vinyl and divinyl ketones for Nazarov cyclization

“…A number of specific methods have been developed for their synthesis, depending on the vinyl substitution pattern desired i,ii,iii,iv,v. For the preparation of substrates with electron-withdrawing groups such as those employed in Lewis acid-catalyzed Nazarov cyclizations of polarized substrates,vi Knoevenagel condensation has been the only option vii.…”