| Germanium lies in the same main group as silicon and tin in the periodic table.However,compared with silicon and tin,research on germanium,especially in the field of organic chemistry,is scattered and scarce.While synthesis of organosilicon and organotin along with their reactions have been intensively studied,those of organogermanium are still underdeveloped.Therefore,this dissertation focus on the synthesis and reaction of a special type of organogermanium,namely alkyl carbagermatranes.In chapter two,synthesis of alkyl carbagermatranes has been expanded to Zn-mediated decarboxylative carbagermatranation of N-(acyloxy)phthalimide.N-(acyloxy)phthalimide can be facially derived from widely occurring and commercial available alkyl carboxylic acid,therefore such decarboxylative carbagermatranation strategy permits convineint installation of complex functional groups in the synthesized alkyl carbagermatranes and presenting major advantages over previous method in which pre-prepared or in situ-generated alkyl organometallic reagents(e.g.alkyl-Mg,alkyl Zn etc.)were used.Mechanistic experiments revealed that N-(acyloxy)phthalimide was initially reduced by Zn to alkyl radicals,which was further reduced to alkyl carbanion and finally participated in the formation of alkyl carbagermatranes.In chapter three,reaction of alkyl carbagermatranes was extended to Catellani reaction from direct cross-coupling reaction.Through palladium/norbornene co-catalysis,alkyl carbagermatranes realized general ipso/rtho dialkylation of aryl iodides,which was not accomplished before.This reaction was compatible with a wide range of substrates scope and functional groups,and allows intramolecular cyclization and late-stage modification of complex molecules such as natural product and drugs derivatives.Other than that,ipso alkylation/ortho arylation was also realized by using aryl bromides as ortho reacting reagents.It is noted that,this reaction was successfully applied in the simple total synthesis of totarol derivatives.In chapter four,enantioselective synthesis of chiral alkyl carbagermatranes was demonstrated.Starting from vinyl carbagermatranes,binucleophilic fragment containing both Ge and B moiety was obtained by enantioselective hydroborylation.By combining copper(Ⅰ)catalyst and chiral phosphine ligand,chiral alkyl carbagermatranes with excellent e.e.value were accessed under mild condition.The resulting chiral alkyl carbagermatranes proved capable of realizing stereospecific palladium-catalyzed cross-coupling reaction. |
