preparation of thermodynamic silyl enol ethers Tetrahedron Letters,Vol.24,No.l3,pp 1345-1348,1983 There now exist a variety of mild and very selective procedures for the kinetic Synthesis of Whereas enols are seen only as a small proportion of the keto-enol tautomerism, silyl enol ethers are stable and very useful sources of regiochemically pure enolate ions. Kinetic and thermodynamic enolate alkylation O 1) NaOEt, RT 2) BnBr O O 1) LDA, –78 °C 2) BnBr O O 1) LDA, –78 °C 2) MeI O O not. The Mander reagent allows the formation of β-ketoesters with quaternary centers, which cannot be done with Claisen condensations under thermodynamic control, since the final enolization step cannot occur. 2.

[7] [8] These reactions employ electron-deficient sulfonyl azides, which undergo chemoselective, uncatalyzed [3+2] cycloaddition to the silyl enol ether, followed by loss of dinitrogen, and alkyl migration to … Wensheng Yu, Zhendong Jin. B Watsona and Douglas Hayesb aDepartment of Pure and Applied Chemistry, WESTChem, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, Scotland, UK GlaxoSmithKline, Medicines Research Centre, Gunnels b Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK. Nonetheless, it is now possible for the first time to selectively prepare the thermodynamic silyl enol ether from an unsymmetrical ketone free from contamination _by _its kinetic regioisomer. European Journal of Organic Chemistry 2001 , 2001 (6) , 1023-1031. Cyclization Reactions of 1,3-Bis-Silyl Enol Ethers and Related Masked Dianions, Langer, P. Synthesis 2002, 441-59. The more stable enolate ion is called the thermodynamic enolate and the faster forming one the kinetic enolate. The relative reactivities of structurally analogous silyl enol ethers, enamines, and enolate anions towards carbon-centered electrophiles are determined as 1, 107, and 1014, respectively. silyl enol ether deriving from an a,a'-dienolizable ketone 1 is a critical step which requires often a preliminary fundionalization or the use of specific reagents of limited avaibility.1 Concerning direct methodologies,314 in most cases a mixture of regioisomeric silyl enol ethers 2 and 3 was obtained. In view of methodology available for rapid and quantitative regeneration6 of enolates from silyl enol ethers, we expect BMDA to become a standard reagent for organic synthesis. Enol silyl ethers can be prepared readily from the parent carbonyl compounds by silylation of the corresponding enolate anions. Silyl synonyms, Silyl pronunciation, Silyl translation, English dictionary definition of Silyl.