Copper-Catalyzed Borylation/Silylation Reactions Of Conjugated Enynes And The Applications Of The Products

Organoboron and organosilicon reagents have been used as very useful and powerful building blocks in the synthesis of pharmaceuticals,natural products,agrochemicals and materials during the past over half century.In this dissertation we developed controllable and selective methods for the synthesis of boron/silicon-containing compounds by using easily available conjugate enynes,bis(pinacolato)diboron and silylboronate as starting materials.Further applications of the corresponding homoallenylboronate products in an unprecedented Suzuki-Miyaura coupling reaction could afford the functionalized 1,3-dienes in good yields and with excellent stereoselectivities.Major work could be divided into three parts:Part One:Divergent protoborylation of CF3-substituted conjugate enynesThere are only sporadic examples on the synthesis of homoallenylboron despite their highly potential worth as four-carbon synthons in organic synthesis.In this part,we developed an efficient copper-catalyzed 1,4-protoborylation of conjugate enynes,a series offfunctionalized homoallenylboronates were accessed in good to excellent yields.On the other hand,the opticafly active homoallenylboro nates were obtained with excellent enantionselectivity with using novel designed bulky chiral bisoxazoline ligand.In addition,a new protocol to yield homopropargylboronates regioselectively was established with using NaNO2 as an additive.Part Two:Unprecedented applications of homoallenylboronates in palladium-catalyzed Suzuki-Miyaura coupling reactions:There is no example on the transformation of homoallenylboron in various cross coupling reactions despite their fickle reactivity and multiple reaction sites.In this part,a series of homoallenylboronates were used as coupling partners to react with phenyl iodides,allyl bromides as well as alkynyl bromides under modified Suzuki-Miyaura coupling reaction conditions.Various multi-substituted 1,3-dienes with good regioselectivity and stereoselectivity were obtained in good yields.Part Three:Nucleophilic silylation of enyne chlorides:In this part,we attempted to use enyne chlorides and silylborane as starting materials to yield different silicon-containing compounds via regioselective nucleophilic substitution process.In the presence of Cu(I)catatyst,various SN2 adducts and SN2’ adducts were obtained in good yields and with excellent regioselectivities under the optimized reaction conditions.Furthermore,the catalytic synthesis of optically active Sn2’ adducts was investigated.When the(Z)-enyne chlorides were evaluated,the corresponding substituted products were obtained with good enantioselectivity and excellent regioselectivity.Fmally,a regioselective vinyl substituted allenylsilane product was formed via a paladium-catalyzed SN2" pathway.