The Influence of the 2-Alkoxy Group and of C-5 Substituents on the Direction of Reductive Cleavage of 2-Alkoxytetrahydrofurans by AlH<sub>2</sub>Cl in Ether Solution
作者:P. C. Loewen、Miss L. P. Makhubu、R. K. Brown
DOI:10.1139/v72-238
日期:1972.5.15
ring C—O bond cleavage. However, substituents at C-5 of 2-methoxytetrahydrofuran exert a strong effect on the ratio of ring to exo C—O bond cleavage. Thus, alkyl (electron donor) groups at C-5 promote an increase in the amount of exo cleavage, the proportion increasing from 62.5 to 100% as the C-5 alkyl group is changed from CH3 to t-C4H9. In contrast, electron withdrawing substituents, CH3OCH2— and
Tandem homologation-acylation chemistry: Single and double homologation
作者:Carley S. Henderson、Jennifer R. Mazzone、Amanda M. Moore、Charles K. Zercher
DOI:10.1016/j.tet.2021.132223
日期:2021.7
Furakawa-variant of the Simmons-Smith reagent results in homologation and production of an intermediate zinc enolate. Treatment of the enolate with various acylating agents generate products with both γ-dicarbonyl functionality and β−dicarbonyl functionality. In situ exposure of the acylated product to additional zinc carbenoid effects a second regiospecific homologation reaction.
Synthesis of β-mercuri ketones by the reaction of siloxycyclopropanes with mercuric acetate and their conversion to α-methylene ketones and γ-ketoesters
Siloxycyclopropanes were quantitatively converted to β-acetoxymercuri ketones by the reaction with mercuricacetate. Successive treatment with palladium chloride or palladium chloride/carbon monoxide gave α-methylene ketones or γ-ketoesters, respectively, in good yields.
A Combined DFT and NMR Investigation of the Zinc Organometallic Intermediate Proposed in the<i>Syn</i>-Selective Tandem Chain Extension–Aldol Reaction of β-Keto Esters
作者:Karelle S. Aiken、Wilhelm A. Eger、Craig M. Williams、Carley M. Spencer、Charles K. Zercher
DOI:10.1021/jo3004925
日期:2012.7.20
esters provides an α-substituted γ-keto ester with an average syn:anti selectivity of 10:1. It is proposed that the reaction proceeds via a carbon–zinc bound organometallic intermediate potentially bearing mechanistic similarity to the Reformatsky reaction. Evidence, derived from control Reformatsky reactions and a study of the structure of the TCA intermediate utilizing DFT methods and NMR spectroscopy