Synthesis of methyl 2-oxo-5-vinyl-2,5-tetrahydrofuran-3-carboxylate
A synthesis of methyl 2-oxo-5-vinyl-tetrahydrofuran-3-carboxylate involving five synthetic steps from commercially available 3,4-dihydroxybutene is reported.
Silvestri, Maximilian A.,He, Chang,Khoram, Anita,Lepore, Salvatore D.
p. 1625 - 1626
(2007/10/03)
Bis(trimethylsilyl) Sulfate Catalysis in γ-Lactonization of Cyclopropanecarboxylates Activated by Carbonyl Substituents on α-Carbon
The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)-C(2) bond cleavage to produce γ-lactones.Stereochemically, the reaction takes two pathways: (1) substrates with a cationstabilizing group like vinyl on C(2) give thermodynamically favored γ-lactones having the thermodynamically more stable arrangement of substituents irrespective of the configuration of the cyclopropane substrates, (2) substrates without such a cation-stabilizing group afford γ-lactones under ca. 70percent inversion at C(2) reaction center.
BIS(TRIMETHYLSILYL) SULPHATE CATALYZED γ-LACTONIZATION OF CYCLOPROPANECARBOXYLATES HAVING A CARBONYL SUBSTITUENT AT CYCLOPROPANE α-CARBON
The oxa analogue of vinylcyclopropane rearrangement in the title system is carried out under mild conditions with the aid of the silicon Lewis acid catalyst.