Synthesis of Tertiary α-Hydroxy Acids by Silylene Transfer to α-Keto Esters
摘要:
alpha-Keto esters can be converted into alpha-hydroxy acids in a single flask involving metal-catalyzed silylene transfer, 6 pi-electrocyclization, Ireland-Claisen rearrangement, and hydrolysis. This reaction sequence is stereoselective and tolerates alkyl- and aryl-substituted a-keto ester substrates as well as an alpha-imino ester.
Synthesis of Tertiary α-Hydroxy Acids by Silylene Transfer to α-Keto Esters
摘要:
alpha-Keto esters can be converted into alpha-hydroxy acids in a single flask involving metal-catalyzed silylene transfer, 6 pi-electrocyclization, Ireland-Claisen rearrangement, and hydrolysis. This reaction sequence is stereoselective and tolerates alkyl- and aryl-substituted a-keto ester substrates as well as an alpha-imino ester.
Silylene transfer to α-keto esters and application to the synthesis of γ-lactones
摘要:
Disubstituted alpha-hydroxy acids have been synthesized by metal-catalyzed silylene transfer to alpha-keto esters. A range of substituents are tolerated in the transformation with the exception of branched groups at the vinylic position. The alpha-hydroxy acid products can be converted into gamma-lactones using a variety of lactonization conditions. (C) 2009 Elsevier Ltd. All rights reserved.
Metal-Catalyzed Rearrangement of Homoallylic Ethers to Silylmethyl Allylic Silanes in the Presence of a Di-<i>tert</i>-butylsilylene Source
作者:Pamela A. Cleary、K. A. Woerpel
DOI:10.1021/ol052456x
日期:2005.11.1
transfer to gem-disubstituted alkenes to form silacyclopropanes, we discovered an unprecedented reaction of homoallylic ethers. When silylene transfer was performed at room temperature or above, two di-tert-butylsilylene units were incorporated into the molecule, and complete rearrangement of the carbon backbone occurred. This report describes the scope of this unique reaction as well as the mechanistic
alkenes and dienes. The first isonitrile insertion products, the silacyclobutanimines 26–28 were synthesized and the structure of 28 was determined by X-ray crystallography. Upon thermolysis 20–22 rearranged quantitatively to furnish the compounds 29–32.
Insertion Reactions of Silacyclopropanes: Evidence for a Radical-Based Mechanism
作者:Christina Z. Rotsides、K. A. Woerpel
DOI:10.1021/acs.organomet.6b00469
日期:2016.9.26
Silacyclopropanes reacted rapidly and selectively with p-benzoquinones, to provide oxasilacyclopentanes. Ring expansion products were observed in the absence of a catalyst, elevated temperatures, or irradiation. As substitution was increased on the silacyclopropane ring, improved stereoselectivity was observed. In some cases, the regiochemistry was controlled depending on the extent of stabilization of the reactive intermediates involved. A radical clock experiment, along with stereochemical studies, confirmed that radical intermediates were involved in the ring-expansion reaction. The scope of this radical reaction was expanded to include dienones, aryl aldehydes, and electron-deficient enones in addition to benzoquinones. In the case of aryl aldehydes and electron-deficient enones, the radical reaction can be used to generate silylenes from silacyclopropanes.
Synthesis of Tertiary α-Hydroxy Acids by Silylene Transfer to α-Keto Esters
作者:Brett E. Howard、K. A. Woerpel
DOI:10.1021/ol702148x
日期:2007.10.1
alpha-Keto esters can be converted into alpha-hydroxy acids in a single flask involving metal-catalyzed silylene transfer, 6 pi-electrocyclization, Ireland-Claisen rearrangement, and hydrolysis. This reaction sequence is stereoselective and tolerates alkyl- and aryl-substituted a-keto ester substrates as well as an alpha-imino ester.