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Studies Directed Toward The Synthesis Of Germacranolides Via [2+2] Cycloaddition Followed By Ring Expansion/Elimination Of Β-Lactones, Bryan E. Yates
Studies Directed Toward The Synthesis Of Germacranolides Via [2+2] Cycloaddition Followed By Ring Expansion/Elimination Of Β-Lactones, Bryan E. Yates
Masters Theses
Exposure of α-trimethylsilyl β-lactones to magnesium bromide or boron trifluoride etherate in diethyl ether solvent resulted in the smooth generation of β,γ-unsaturated acid derivatives in good yield and isomeric purity. It is believed that this reaction occurs via the formation of a stable tertiary carbocation at the γ-carbon resulting from cleavage of the carbon-oxygen sigma bond due to the complexation of the Lewis acid with the ring oxygen atom. Rapid loss of an adjacent electrofuge then furnishes the unsaturated acids. The β-lactone precursors were prepared by a [2+2] cycloaddition of an aldehyde and an alkyl trimethylsilyl ketene. This method was …