Palladium-catalyzed olefination of aryl/alkyl halides with trimethylsilyldiazomethane via carbene migratory insertion

Abstract

One-pot formation of (E)-vinyl silanes and (E)-silyl-substituted α, β-unsaturated amides could be completed easily via palladium carbene migratory insertion in good yields and high chemoselectivity.

Asymmetric Hydrosilylation of β-Silyl Styrenes Catalyzed by a Chiral Palladium Complex

“…Compound 1p (1.7 g) was prepared from 1-ethynyl-4-(trifluoromethyl)­benzene (1.70 g, 10.0 mmol) and chlorotrimethylsilane (1.08 g, 10.0 mmol) by the procedure for the preparation of 1a , and the yield was 70% (from 1-ethynyl-4-(trifluoromethyl)­benzene), known compound: R f = 0.79 (PE); 1 H NMR (CDCl 3 , 400 MHz): δ 7.61 (d, J = 8.0 Hz, 2H), 7.55 (d, J = 8.0 Hz, 2H) 6.94 (d, J = 19.2 Hz, 1H) 6.64 (d, J = 19.2 Hz, 1H) 0.22 (s, 9H). 13 C { 1 H} NMR (CDCl 3 , 100 MHz, plus, APT): δ (up) 141.7 (s), 129.8 (d, J = 32.0 Hz): δ (down) 142.2 (s), 133.1 (s), 126.5 (s), 125.4 (q, J = 4.0 Hz), −1.5 (s).…”

“…(E)-(3-Chlorostyryl) Trimethylsilane (1l). Compound 1l (1.6 g) was prepared from 1-chloro-3-ethynylbenzene (1.37 g, 10.0 mmol) and chlorotrimethylsilane (1.08 g, 10.0 mmol) by the procedure for the preparation of 1a, and the yield was 76% (from 1-chloro-3ethynylbenzene), known compound: 29 3, 131.4, 129.8, 127.9, 126.4, 124.7, −1.16.…”

Stereoselective Cyclopropanation of 1,1-Diborylalkenes via Palladium-Catalyzed (Trimethylsilyl)diazomethane Insertion

“…Similar direct olefination of aryl/alkyl halides with (trimethylsilyl)methylene was observed by Chen and Xu to occur via carbene migratory insertion in the presence of palladium complexes. 21 The cyclopropanation of 2-cyclohexyl 1,1-diborylalkene ( 2h ), 2-cyclohexenyl 1,1-diborylalkene ( 2i ), and 2-(3-thiophenyl) 1,1-diborylalkene ( 2j ) did not progress toward the desired product, suggesting an inhibited migratory insertion of the alkene into the Pd=CH-TMS intermediate, as a consequence of the lower electrophilic character of C 2 .…”

Synthesis of Functionalized Vinylsilanes via Metal-Free Dehydrogenative Silylation of Enamides

“…Vinylsilanes are very useful synthetic intermediates in organic synthesis and building blocks in organic material science . Accordingly, a variety of methods are known for the preparation of vinylsilanes, such as the transition-metal-catalyzed hydrosilylation of alkynes or allenes, cross-coupling reactions, Wittig/Peterson olefination, the addition of vinyl Grinard reagents or vinyllithiums to silyl electrophiles, and so on. However, the difficulty in controlling the regioselectivity and stereoselectivity of products as well as the limitations of the harsh reaction conditions still spur chemists to discover new and practical methods.…”