Study On C-C Bonding Formation Reaction Of Alkenyl Carbon As Nucleophiles

Alkenyl compounds are widely used in organic synthesis,and they are also good nucleophiles for C-C or C-X bonding formation.In this thesis,oxetanes and esters were selected as electrophiles,while alkenyl compounds were used as nucleophiles to realize C-C bonding reaction,which was used to construct a series of organic skeletons.The specific work is as follows:（1）Intermolecular ring opening reaction of oxetanes with carbon nucleophilicUnder the catalysis of 10 mol%LiNTf₂,the ring-opening reaction between silyl enol ether and oxetane was carried out.The maximum obtained yield ofδ-hydroxyl ester derivatives is 93%after one hour of reaction in DCE at room temperature.With the catalysis of TBSNTf₂,the in situ generated-hydroxyl ester derivatives can further transform into theζ,ε-dihydroxyβ-ketoesters via Claisen condensation.The C（Sp³）-C（Sp³）bonding formation reaction with alkenyl group as a nucleophile was realized.The mechanism study showed that although LiNTF₂ and TBSNTf₂ were Lewis acids,their catalytic effects were obviously different.（2）Intramolecular ring opening reaction of oxetanes with carbon nucleophilicWe designed and synthesized oxetane derivatives with alkenyl substituents.Under the catalysis of 10 mol%Sc（OTf）₃ with 20 mol%Ph BOX as ligand,dihydrobenzo[b]oxepine derivatives were synthesized through intramolecular ring-opening reaction of oxetanes,the maximum yield was up to 99%.In additional,the chiral Box ligand can also be used to synthesize the chiral dihydrobenzo[b]oxepine derivatives with82%ee.The above reactions all have good tolerability of functional groups.Finally,under the catalysis of 5.0 mol%B（C₆F₅）₃,dioxacyclo[3.2.2]nonane derivatives can be synthesized by the reactions of the same substrates in DCM at 60 ^oC for 12 hours,and the yield were62%-98%.（3）Claisen condensation reaction catalyzed by Lewis acidUnder the catalysis of TBSNTf₂,1,3-dicarbonyl compounds can be synthesized by Claisen condensation of esters and silyl enol ether.The yield of 1,3-dicarbonyl compounds were 44%-93%.The esters containing electron-donating and electron-withdrawing substituents and heteroarylcycloesters can be tolerated.