3-Unsubstituted 1,5-Diaryl-2,4-pentanediones and -4-methoxy-2-pentanones: Synthesis via Corresponding 3-Hydroxy Ketones Generated from 2-Isoxazolines
摘要:
Aryl acetaldoximes are reacted with allylarenes in the presence of sodium hypochlorite to give 3,5-bis(arylmethyl)-2-isoxazolines which are then converted to 1,5-diaryl-4-hydroxy-2-pentanones by a reductive hydrogenation in the presence of water. These intermediate aldols can then be either oxidized with Corey-Kim reagent to stable dimethylsulfonium 1-(arylacetyl)-2-oxo-3-arylpropylides followed by zinc-acetic acid reduction to give 1,5-diaryl-2,4-pentanediones, or converted to 1,5-diaryl-4-methoxy-2-pentanones by refluxing in methanol in the presence of hydrochloric acid. A detailed study of this general route is reported here.
Abstract The enantioselectivesynthesis of (S)-(−)-spirobrassinin, which features a unique sulfur-containing spirooxindole skeleton, was achieved by focusing on the phytoalexin generation in Brassicaceae plants. Specifically, (S)-(−)-spirobrassinin was obtained in a one-pot fashion from l-tryptophan through a reaction involving S-spirocyclization with various turnip enzymes and constituents, i.e.,
Homologation of arylaldehydes provides useful synthetic intermediates, but it requires multistep reactions and generates significant amounts of waste. We considered such reactions using nitromethane as a C1 source through nitroolefin formation, partial hydrogenation to oximes, and hydration of oximes; however, the control of selectivity in the second reaction is challenging. To achieve this pathway
Synthesis, analysis and rearrangement of novel unnatural glucosinolates
作者:Nicola E. Davidson、Trevor J. Rutherford、Nigel P. Botting
DOI:10.1016/s0008-6215(00)00308-6
日期:2001.2
As part of a structure activity study to examine the interaction of glucosinolates with leaf surfaces,a number of glucosinolates were synthesised bearing novel side chain functionalities. These included 7-carboxyheptyl, heptyl, and naphthyl side chains. For the carboxyheptyl glucosinolate, a novel intramolecular rearrangement reaction was observed during the final deprotection step, which generated an ester attached to the C-3 of glucose. Studies by H-1 NMR spectroscopy showed that the hydrophobic side chain associated with one face of the glucose ring and it was proposed that this was the driving force for the rearrangement. Similar hydrophobic interactions were also observed between the heptyl and naphthyl side chains and the glucose. (C) 2001 Elsevier Science Ltd. All rights reserved.
Mayer,F.; Sieglitz, Chemische Berichte, 1922, vol. 55, p. 1854
作者:Mayer,F.、Sieglitz
DOI:——
日期:——
3-Unsubstituted 1,5-Diaryl-2,4-pentanediones and -4-methoxy-2-pentanones: Synthesis via Corresponding 3-Hydroxy Ketones Generated from 2-Isoxazolines
作者:Juha T. Pulkkinen、Jouko J. Vepsäläinen
DOI:10.1021/jo960887a
日期:1996.1.1
Aryl acetaldoximes are reacted with allylarenes in the presence of sodium hypochlorite to give 3,5-bis(arylmethyl)-2-isoxazolines which are then converted to 1,5-diaryl-4-hydroxy-2-pentanones by a reductive hydrogenation in the presence of water. These intermediate aldols can then be either oxidized with Corey-Kim reagent to stable dimethylsulfonium 1-(arylacetyl)-2-oxo-3-arylpropylides followed by zinc-acetic acid reduction to give 1,5-diaryl-2,4-pentanediones, or converted to 1,5-diaryl-4-methoxy-2-pentanones by refluxing in methanol in the presence of hydrochloric acid. A detailed study of this general route is reported here.