94286-53-0Relevant academic research and scientific papers
A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
, p. 3331 - 3350 (2007/10/02)
Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
Photochemical 1,3-Silyl Migration in Allylsilanes Occurring with Inversion of Silyl Configuration
Kira, Mitsuo,Taki, Takayuki,Sakurai, Hideki
, p. 5647 - 5648 (2007/10/02)
In apparent disagreement with the prediction by the Woodward-Hoffmann rule, facile intramolecular 1,3-silyl migration of allyl- and propargylsilanes with aromatic substituents at the silicon atom took place reversibly in various solvents under irradiation with 254-nm light, accompanied by the inversion of the silyl configuration.
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.
A Synthesis of Allylsilanes in which the Silyl Group is at the More-substituted End of the Allyl Group
Fleming, Ian,Waterson, David
, p. 1809 - 1813 (2007/10/02)
The allylsilanes (8), (11), (18) - (20), and (26), have been made by a three-step sequence from αβ-unsaturated esters.The steps are conjugate addition of the phenyldimethylsilyl group, lithium aluminium hydride reduction, and selenium-mediated dehydration
