226710-79-8Relevant academic research and scientific papers
Oxidative rearrangement of 2-furylcarbamates with dimethyldioxirane: A high-yielding preparation of 5-hydroxypyrrol-2(5H)-ones
Boukouvalas, John,Loach, Richard P.,Ouellet, Etienne
, p. 5047 - 5050 (2011)
A mild, general and efficient method for the oxidative rearrangement of 2-furylcarbamates to N-Boc-5-hydroxypyrrol-2(5H)-ones is reported. The feasibility of removing the Boc group from the products was demonstrated by the synthesis of two hitherto unknown 5-aryl-5-hydroxypyrrol-2(5H)-ones.
Cycloaddition-Rearrangement Sequence of 2-Amido Substituted Furans as a Method of Synthesizing Hexahydroindolinones
Padwa, Albert,Brodney, Michael A.,Satake, Kyosuke,Straub, Christopher S.
, p. 4617 - 4626 (2007/10/03)
A convenient synthesis of various substituted hexahydroindolinones has been achieved by an intramolecular Diels-Alder cycloaddition (IMDAF) reaction of 2-amido substituted furans. The initially formed [4 + 2] cycloadduct undergoes nitrogen-assisted ring opening followed by deprotonation of the resulting zwitterion to give the rearranged ketone. The stereochemical outcome of the IMDAF cycloaddition has the sidearm of the tethered alkenyl group oriented syn with respect to the oxygen bridge. The reaction rate and product yield were found to be markedly dependent upon the electronic properties of the alkenyl π-bond. 2-[2-(tert-Butoxycarbonylfuran-2-yl-amino)-ethyl]acrylic acid methyl ester was synthesized from 3-chlorocarbonyl-but-3-enoic acid methyl ester. Thermolysis of the carbomethoxy activated furanamide occurred at 80 °C to produce a rearranged hexahydroindolinone. When Me3Al or (MeO)3Al was used as a Lewis acid to promote the cycloaddition, a rearranged alcohol was obtained. The initially formed [4 + 2] cycloadduct undergoes ring opening in the presence of the Lewis acid, and the resulting aluminum intermediate delivers the substituent group from the same face as the neighboring oxygen to ultimately furnish a rearranged cis-alcohol. In contrast to this result, a mixture of diastereomeric methoxy alcohols was isolated when the IMDAF cycloaddition was carried out in methanol. The major isomer corresponds to the trans-diastereomer that results from trapping of the iminium ion from the less crowded face of the π-bond.
A Cycloaddition Approach toward the Synthesis of Substituted Indolines and Tetrahydroquinolines
Padwa, Albert,Brodney, Michael A.,Liu, Bing,Satake, Kyosuke,Wu, Tianhua
, p. 3595 - 3607 (2007/10/03)
The intramolecular Diels-Alder reaction of 2-substituted aminofurans (IMDAF) results in the formation of various indolines and tetrahydroquinolines. The isolation of these ring systems from the IMDAF reaction can be rationalized in terms of an initial [4 + 2]-cycloaddition that first produces an oxa-bridged cycloadduct, which was not detected since it readily underwent nitrogen-assisted ring opening. Proton exchange followed by an eventual dehydration provides the aromatic product. In certain cases, the intermediate cyclohexadienol can be isolated and independently converted to the final product in high yield. The starting 2-aminofurans were readily prepared from furanyl acyl azide by a Curtius rearrangement in the presence of an alcohol. Alkylation of the resulting N-alkyl carbamate with an alkenyl bromide allows for the synthesis of a wide variety of cycloaddition precursors. The scope of the IMDAF reaction was evaluated by using mono- and disubstituted alkenes, electron rich and electron deficient olefins, and acetylenic tethers. Cyclic 2-amidofurans were also synthesized using a related intramolecular Diels-Alder reaction of 2-amido-substituted oxazoles which contain a tethered alkyne. This transformation represents a new route to this rare heterocyclic ring system. The sequential cycloaddition method was used for a formal synthesis of the pyrrolophenanthridone alkaloid hippadine.
