Study On Synthesis And Reaction Chemistry Of The New Hydrosilylalkynes

Hydrosilylanes are an important class of organic compounds that are commonly used as hydrogenation agents in organic synthesis and organometallic synthesis.However,the hydrosilylanes with formula of RnSiH4-n(R,hydrocarbon group)are often inert directly toward the substrates.Therefore,great effert has been persuited on improving their reactivity with respect to the Si-H bond reaction.In this thesis,we make functionalization of the Si center by linkage of the Lewis acid group and then develop a series of new hydrosilyl compounds that are effectively reactive toward a wide range of organic molecules.Three charpters are contained as follows.1· Studies on synthesis and reaction chemistry of arylaminohydrosilylboranesIn this work,a suitable method for synthesis of an arylamino-hydrisilylborane was developed.The arylaminohydrosilyl chloride Ar(R3Si)NSiMeHCl was prepared by a double deprotonation-salt elimination reaction using ArNH2 as a raw material.Ar(R3Si)NSiMeHCl reacted with PhC?CLi by salt elimination reaction to form Ar(R3Si)NSiMeH(C?CPh)(1-lb-1-lc)that further reacted with B(C6F5)3 under 1,1-carboboration to give pentafluorophenylboron-containing arylaminohydrosilyl-borane compounds 2,6-iPr2C6H3N(SiMePh2)SiMe(H)C(Ph)=C(C6F5)B(C6F5)2(1-2b)and 2,4,6-Me3C6H2N(SiMe2Ph)SiMe(H)C(Ph)=C(C6F5)B(C6F5)2(1-2c).Compounds 1-2b and 1-2c were characterized by spectroscopy and X-ray crystallography.The structures of these two compounds are similar to the previously reported compound 2,6-iPr2C6H3N(SiMePh2)SiMe(H)C(Ph)=C(C6F5)B(C6F5)2(1-2a).Furthermore,reactions using 1-2a with sixteen alcohol molecules were explored,which exhibited two types of the reactions.One is hydrodeoxygenation under H2-elimination to produce olefinic products and another is the hydrodeoxygenation without H2-elimination to form alkane products.For substrates such as 1-phenylethanol(1-4a),1-(4-chlorophenyl)ethanol(1-4c),1-(4-bromophenyl)ethanol(1-4d),1-(3-chlorobenyl)ethanol(1-4e),1-(4-trifluoromethylphenyl)ethanol(1-4f),1-(3,5-ditrifluoromethylphenyl)ethanol(1-4g),2-phenyl-2-ethanol(1-4h)and 1,1-diphenylethanol(1-4i),the first reaction way was undertaken,generating olefinic compounds 1-5a and 1-5c-1-5i.For 1-(4-methoxyphenyl)ethanol(1-4b),the second conversion was applied to yield 1-(4-methoxyphenyl)ethane(1-6b).When 1-(4-methylphenyl)ethanol(1-4j),1-(2-naphthyl)ethanol(1-4k),1,2,3,4-tetrahydro-1-naphthol(1-41)and 1-(4-biphenyl)ethanol(1-4m)were treated,both two reaction ways were conducted,producing a mixture of olefinic and alkane products.In addition,reactions of 1-2a with borneol,cedarol and sterol were also investigated,in which borneol and cedarol proceeded through the first conversion to form the olefinic compounds 1-5n and 1-5o,respectively,while sterol underwent the second conversion to form alkane 1-6p.2.Studies on reaction chemistry of phosphanylhydrosilylalkynes and B(C6F5)3Ph2PC?CSiHMe2(2-la),(4-MeC6H4)2PC?CSiHMe2(2-1b),(4-tBuC6H4)2PC?C-SiHMe2(2-1c)and(2,4,6-Me3C6H4)Ph2PC?CSiHMe2(2-1d)were prepared by using a C?C-centered,there-folded substituent transformation starting from Me3SiC?CH.The reactions using these four compounds respectively with B(C6F5)3 were carried out.Compound 2-la reacted with B(C6F5)3 to form two different stereo structured olefinic products[(E)-(C6F5)3BC(H)=C(PPh2)SiMe2]2(2-2a)and(Z)-(C6F5)2BC(H)=C(PPh2)-SiMe2(C6F5)(2-3a).The same reaction way was exhibited for 2-1b and B(C6F5)3,leading to compounds {(E)-(C6F5)3BC(H)=C-[P(4-MeC6H4)2]SiMe2}2(2-2b)and(Z)-(C6F5)2BC(H)=C[P(4-MeC6H4)2]SiMe2(C6F5)(2-3b).Compound 2-lc reacted with B(C6F5)3 to give ?(E)-(C6F5)3BC(H)=C[P(4-tBuC6H4)2]SiMe2}2(2-2c)and 2-1d with B(C6F5)3 to(Z)-(C6F5)2BC(H)=C[P(2,4,6-Me3C6H2)2]SiMe2(C6F5)(2-3d).All of these products were characterized by NMR and X-ray crystallography.The temperature-dependent kinetic studies on reaction of 2-1 a with B(C6Fs)3 and that of 2-1 d with B(C6F5)3 were also carried out.Theoretical calculations were performed as well.These studies are performed in attempt to understand the reaction mechanism.Generally,the above reactions are probably involved in the formation of the silicon cation as Me2HSi+ followed by the Si-H addition across the C?C bond.This reaction way may be considered as a self-hydrosilylation and represents as a new way so far reported.Furthermore,in the reaction of 2-lb with B(C6F5)3,a BC2-ternary ring compound H2CB[(C6F5)2]CSi(Me2)P[(4-MeC6H4)2](r/2-C6F4)(2-4)was also isolated.Ph2PC?CSiHMes2(Mes=2,4,6-Me3C6H2,2-1e)and Ph2PC?CSiHPh2(2-lg)were synthesized by a similar method.For comparative study,PhC?CSiHMes2(2-lf),PhC?CSiHMe](2-1h)and nBuC ?CSiHMe2(2-li)were also synthesized.Compound 2-1e reacted with B(C6F5)3 to form a P?B coordination compound(C6F5)3B?P(Ph2)C?CSiHMes2(2-5)and further a 1,1-carboboration product(E)-(C6F5)B(C6F5)2C=C(PPh2)SiHMes2(2-6).Compound 2-1f reacted with B(C6F5)3 to afford 1,1-carboboration compound(Z)-(C6F5)(C6F5)2BC=C(Ph)SiHMes2(2-7).Both 2-lg and 2-lh reacted with B(C6F5)3 to yield a mixture of products as either a self-hydrosilation or a 1,1-carboboration.Compound 2-li reacted with B(C6F5)3 to give a Si-F-B heterocycle(E)-SiMe2(F)(nBu)C=C(C6F5)B(C6F5)2(2-8).These studies indicate a great influence on the formation of the products by changing the alkyne substituent group.3· Studies on reaction chemistry of the respective P/B and P/Si+FLPsCompounds 2-2a,2-2b and 2-2c can be considered as a P/Si+Frustrated Lewis Pair(FLP)while 2-3a,2-3b,2-3d and 2-6 as the P/B FLP.The reaction chemistry using these two FLPs was herein studied.Compound 2-2a reacted with acetophenone by the C=O bond activation cycloaddition to form a C2SiPO-five-membered heterocycle[(C6F5)3BC(:H)=C(PPh2)SiMe2][O-C(Me)(Ph)](3-1),and with tert-butyl isocyanate by the similar way to[(C6F5)3BC(H)=C(PPh2)SiMe2][O-C(=N/Bu)](3-2).Moreover,2-2a reacted with p-methylbenzonitrile to give a C2SiPN-five-membered heterocycle[(C6F5)3BC(H)=C(PPh2)SiMe2][N=C(4-MeC6H4)](3-5).It was novel that 2-2a was able to cleave H2O into a Si-O-Si bridge compound[(FSC6)3BC(H)=C(PPh2)SiMe2]2O(3-6).Compound 2-2c also cleaved H2O to form{(F5C6)3BC(H)=C[P(4-tBUC6H4)2]SiMe2}2O(3-7).It also reacted by the C=O bond activation cycloaddition with tert-butyl isocyanate to give compound,similar to 3-2,that further reacted with H2O penetrated in pyridine solvent to give a hydrolysis product(E)-(F5C6)3BC(H)=C[P(4-tBuC6H4)2C(O)NHtBu][Si(Me2)OH(NCSH5)](3-4).Compound 2-3a reacted with acetophenone to give cycloaddition product{(F5C6)2BC(H)=C[SiMe2(C6F5)]P(Ph2)}[C(Me)(Ph)-O](3-8)and with tert-butyl isocyanate to ?(F5C6)2BC(H)=C[SiMe2(C6F;)]P(Ph2)?[C(=NtBu)-O](3-9).