Organosilicon Compounds-involving Catalytic Selective Allylic Alkylation Reactions

Allylic alkylation reaction is one of the most important organic reactions in the field of organic synthesis, that has been applied successfully in the construction of various functional compounds through C-H, C-C, C-O, C-N, C-S, and other carbon-heteroatoms bond-forming approaches. Especially in the past decades, selective allylic alkylation, including catalytic asymmetric allylic alkylation(AAA reaction), has been attracted much attentions. In this thesis, we want to report our findings on the selective allylic alkylation in the presence of organosilicon compounds by novel catalyst system as well as highly enantioselective allylic alkylation reactions.Firstly, we have disclosed that chlorotrimethylsilane(TMSCl) was a highly efficient catalyst in the allylic alkylation of 1,3-diaryl-2-propenyl acetates with diethylzinc reagent. In this reaction, various 1,3-diaryl-2-propenyl acetates are efficiently transferred to 1,3-diarylpent-1-enes in good to excellent yields. Although allylic alkylation of allylic substrates with organometallic reagents has been reported with copper catalysis, this is the first example that the simple silicon-based Lewis acid, TMSCl, could be applied in the intermolecular allylic alkylation of organozinc reagent.Secondly, we have developed a new approach for the enantioselective palladium-catalyzed allylic alkylation of unsubstituted 2-cyanoacetates using BINOL-derived multifunctional N,O,P-ligand(HZNU-Phos). The catalytic AAA reaction with most of substrates proceeds in high diastereo- and enantioselectivity(up to >99:1 dr and up to 96%ee) though in some cases the enantioselectivity and diastereoselectivity was moderate.Last, based on the previous work, although the corresponding products of the catalytic asymmetric allylic alkylation of 2-cyanoacetates has been fully characterized by NMR, chiral HPLC, and the electronic circular dichroism(ECD), the absolute configuration was left undetermined for the lack of X-ray crystal structure due to its liquid form. Thus we tried to use the experimental electronic circular dichroism(ECD) spectra in combination with time-dependent density functional theory(TDDFT) calculation to determine the absolute configuration of the product is(R,S)-1.