טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentLiron Oskar
SubjectMerging Allylic Carbon-Hydrogen and Carbon-Carbon Bond
Activations en-route to Sophisticated
Molecular Framework
DepartmentDepartment of Chemistry
Supervisor Full Professor Marek Ilan
Full Thesis textFull thesis text - English Version


Abstract

Recently, our group has developed the zirconocene-mediated ring opening of alkylidenecyclopropanes (ACPs) and w-ene cyclopropanes derivatives, via a unique and selective merging of allylic carbon-hydrogen and carbon-carbon bond activations, leading to bismetallated zirconocene complex. The addition of two different electrophiles gives bisfunctionalized acyclic molecules in excellent yields. By diversifying the nature of the two electrophiles, two stereogenic centers were created with high diastereoselectivity.

In this context, we proposed to enlarge the scope of this process by creating three stereogenic centers in an acyclic product via a one-pot sequence, while studying the diastereoselectivity.

Since zirconocene-mediated ring opening was done with stoichiometric amount of zirconocene complex, we tried to develop a catalytic process for the ring cleavage applied on ACPs derivatives, based on the successful catalytic carbozirconation on multiple bonds.

A deeper mechanistic understanding of the combined allylic carbon-hydrogen and carbon-carbon bond activations pathway was also proposed, using labeled experiments.

Finally, we applied our zirconocene-mediated ring opening methodology to the synthesis of the two enantiomers of deuterated neopentane: the smallest enantiomerically enriched hydrocarbons that possess an all-carbon quaternary stereocenter, that is, a carbon center with four different non-hydrogen substituents. Using advanced and sensitive methods, we successfully determined their absolute configuration.