108733-47-7Relevant academic research and scientific papers
Anion-Catalyzed Reactions of Silyl Ester Polyenolates with Electrophiles
Hertler, Walter R.,Reddy, Gade S.,Sogah, Dotsevi Y.
, p. 3532 - 3539 (2007/10/02)
The stereochemical assignments for the trimethylsilyl ester polyenolates 1, 2, and 3 have been made.Unlike simple silyl ketene acetals, 1, 2, and 3 are obtained predominantly as the thermodynamic Z isomers.Bifluoride-catalyzed equilibration studies showed the equilibrium compositions of 1, 2, and 3 to be 89percent Z, 67percent Z, and 95percent 1-Z,3-E, respectively.The regiochemistry of the bifluoride-catalyzed Reformatsky-type reaction of benzaldehyde with 1, 2, and 4 was determined.Regiochemical control of the condensation of 1 with benzaldehyde by reaction temperature was demonstrated, with 95percent α reaction at -95 deg C and 99percent γ-reaction at +34 deg C.Mechanism studies are consistent with a dissociative process in which a dienolate reacts with benzaldehyde at the α position to give the kinetic-controlled product, and as the reaction temperature increases, increasing amounts of the thermodynamic γ product are formed.A nondissociative cyclic process leading to α product may occur at low temperatures.The naked ester dienolate prepared by reaction of 1 with TASF and removal of the resulting fluorotrimethylsilane was alkylated by benzyl bromide exclusively at the α position at -100 deg C.The bifluoride-catalyzed reverse reaction of 1 with benzaldehyde is much slower than the processes that determine the regiochemistry in the forward reaction.
Regioselective Carboxylation of Silicon-Stabilized Allylic Carbanions and the Synthetic Utility of 2-Silyl-3-butenoates
Uno, Hidemitsu
, p. 2471 - 2480 (2007/10/02)
Carbanions of allylic dimethylphenylsilanes show remarkable regioselectivity toward carboxylation with carbon dioxide and methylation with methyl iodide.Methylationn of these compounds occurred preferentially at α position, although allyltrimethylsilane and allyltriphenylsilane are known to give γ selectivity toward the same electrophiles.Moreover, their aluminum "ate" complexes react with carbon dioxide regioselectively at the α position irrespective of methyl substitution pattern of the allylic moieties.The α-carboxylated allylic silanes proved to be useful synthons of 3-(methoxycarbonyl)allyl anions after esterifiaction.
