Process for reducing 3-heteroaryl-3-oxopropionic acid derivatives
申请人:——
公开号:US20030225274A1
公开(公告)日:2003-12-04
The present invention relates to a process for preparing stereoisomerically enriched 3-heteroaryl-3-hydroxycarboxylic esters by reducing 3-heteroaryl-3-oxocarboxylic esters in the presence of ruthenium-containing catalysts.
Noncanonical Cation−π Cyclizations of Alkylidene β-Ketoesters: Synthesis of Spiro-fused and Bridged Bicyclic Ring Systems
作者:Dylan E. Parsons、Alison J. Frontier
DOI:10.1021/acs.orglett.9b00094
日期:2019.4.5
conditions employed, it is possible to achieve selective synthesis of the three different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, and [4.3.1] bridged bicyclicringsystems. All three reactions begin with 6-endo addition of an olefin to the alkylidene β-ketoester electrophile, followed by one of three different cation capture events.
作者:Hamish McNab、James Montgomery、Simon Parsons、David G. Tredgett
DOI:10.1039/c0ob00116c
日期:——
Pyrrolizine-1,3-dione 4 was made by oxidation of the alcohol 2 using pyridinium chlorochromate. The dione 4 shows ketone properties (e.g. formation of DNP derivative 11) and, in common with other pyrrolizinones, the lactam unit is readily ring-opened by methanol under basic conditions. The active methylene unit of 4 couples readily with diazonium salts to provide the hydrazone 15 whose structure was confirmed by X-ray crystallography. The ‘Meldrumsated’ derivative 18 exists exclusively as the tautomer 18F; flash vacuum pyrolysis (FVP) of 18 at 700 °C gives the pyronopyrrolizine 20 exclusively. Reaction of 4 with DMF acetal gives the dimethylaminomethylene derivative 22 which exists as a mixture of rotamers at room temperature.
A Highly Reactive Dicationic Iridium(III) Catalyst for the Polarized Nazarov Cyclization Reaction
作者:Tulaza Vaidya、Abdurrahman C. Atesin、Ildiko R. Herrick、Alison J. Frontier、Richard Eisenberg
DOI:10.1002/anie.201000100
日期:2010.4.26
Pushing the Nazarov envelope: An electrophilic complex (1; see scheme; EDG=electron‐donating group, EWG=electron‐withdrawing group, binap=2,2‐bis(diphenylphosphanyl)‐1,1‐binaphthyl) exhibits unusual catalytic activity in the polarizedNazarovcyclizationreaction. Aryl vinyl ketones that show poor reactivity with well‐known catalysts can be readily cyclized with 1/AgSbF6 (1:1) under mild reaction conditions
Iodolium salts as halogen-bond donor catalysts in the Nazarov cyclization: the molecular oxygen enigma
作者:Avery J. To、Graham K. Murphy
DOI:10.1039/d2nj02731c
日期:——
Nazarov cyclizations of activated precurosrs are achieved under iodolium catalysis, provided that oxygen is present for catalyst activation and turnover.