21008-39-9Relevant academic research and scientific papers
Synthesis of Functionalized Indolines and Dihydrobenzofurans by Iron and Copper Catalyzed Aryl C-N and C-O Bond Formation
Henry, Martyn C.,Senn, Hans Martin,Sutherland, Andrew
, p. 346 - 364 (2019/01/08)
A simple and effective one-pot, two-step intramolecular aryl C-N and C-O bond forming process for the preparation of a wide range of benzo-fused heterocyclic scaffolds using iron and copper catalysis is described. Activated aryl rings were subjected to a highly regioselective, iron(III) triflimide-catalyzed iodination, followed by a copper(I)-catalyzed intramolecular N-or O-arylation step leading to indolines, dihydrobenzofurans, and six-membered analogues. The general applicability and functional group tolerance of this method were exemplified by the total synthesis of the neolignan natural product, (+)-obtusafuran. DFT calculations using Fukui functions were also performed, providing a molecular orbital rationale for the highly regioselective arene iodination process.
Diastereoselective and Enantioselective Conjunctive Cross-Coupling Enabled by Boron Ligand Design
Myhill, Jesse A.,Wilhelmsen, Christopher A.,Zhang, Liang,Morken, James P.
supporting information, p. 15181 - 15185 (2018/11/30)
Enantio- and diastereoselective conjunctive cross-coupling of β-substituted alkenylboron "ate" complexes is studied. Whereas β-substitution shifts the chemoselectivity of the catalytic reaction in favor of the Suzuki-Miyaura product, use of a boronic este
Concise asymmetric synthesis of (+)-conocarpan and obtusafuran
Chen, Cheng-Yi,Weisel, Mark
, p. 189 - 192 (2013/02/26)
The asymmetric synthesis of three natural products: (+)-conocarpan, both (+)- and (-)- obtusafuran is disclosed. The highlights of the synthesis are the enantioselective hydrogenation of prochiral ketones via dynamic kinetic resolution to afford chiral alcohols. Intramolecular ring closure via either Sr reaction or metal-catalyzed C-O bond formation led to the construction of the trans-dihydrobenzofuran core. Georg Thieme Verlag Stuttgart · New York.
Stereospecific Lewis Acid-Promoted Reactions of Styrenyl Systems with 2-Alkoxy-(6-alkyl)-1,4-benzoquinones: Scope, Limitations, and Synthetic Applications
Engler, Thomas A.,Combrink, Keith D.,Letavic, Michael A.,Lynch, Kenneth O.,Ray, James E.
, p. 6567 - 6587 (2007/10/02)
Titanium(IV)-promoted reactions of various (E)-1-propenylbenzenes with 2-methoxy- and 2-methoxy-6-methyl-1,4-benzoquinones produce trans 2-aryl-6-methoxy-3-(and 4-di)methyl-2,3-dihydro-5-benzofuranols (10-12), rel-(1S,6R,7R,8R)-3-methoxy-8-aryl-7-(and 1-di)methylbicyclooct-3-ene-2,5-diones (2 + 2 cycloadducts, 13-15) and/or rel-(1R,5R,6R,7R)-7-aryl-3-hydroxy-6-(and 4)-methylbicyclooct-3-ene-2,8-diones (5 + 2 cycloadducts, 16/17).In many cases, each of the three products can be obtained selectively in good yield by control of reaction conditions and/or by choice of substituents on the quinone or the propenylbenzene.The dihydrobenzofurans are formed stereoselectively, whereas the formation of the bicyclo systems are stereospecific processes.Thus, reactions of (Z)-1-propenylbenzenes afford rel-(1R,6S,7R,8R)-8-aryl-3-methoxy-7-methylbicyclooct-3-ene-2,5-diones (24, 25).No bicyclosystems are found in reactions of the (Z)-propenylbenzenes.The products all apparently result from a thermally allowed 2? + 4? (2 + 5) cycloaddition of the propenylbenzene with a 2-methoxy-4-oxo-2,5-cyclohexadienyl carbocation intermediate (26) formed by coordination of the Ti(IV) to the C-1 carbonyl oxygen of the quinone.In the cycloaddition, the aryl ring of the propenylbenzene occupies an endo position with respect to the pentadienyl carbocation moiety of 26 and the bicyclo carbocation product of the cycloaddition (28/29) either undergoes dealkylation or rearrangement to yield the observed products.Treatment of the bicylo systems with protic acid effects their rearrangement to the dihydrobenzofuranols.Reactions of 2-propenylbenzenes and arylcycloalkenes with the quinones regioselectively give dihydrobenzofuranols 43-45 and 49-54, respectively; a 2 + 2 cycloadduct is found in low yield in only one case.The 7-aryl-3-hydroxy-6-methylbicyclooct-3-ene-2,8-diones are produced exclusively in reactions of 2-((4-methoxybenzyl)oxy)-1,4-benzoquinones with various propenylbenzenes.Application of these reactions to the synthesis of (+/-)-obtusafuran, (+/-)-liliflol-B, (+/-)-kadsurenone, and (+/-) denudatin are reported.
Selective Control of the Various Cycloaddition Products from Reactions of Styrenes and 1,4-Benzoquinones: Optimization of the Formal 5 +2 Cycloadducts
Engler, Thomas A.,Letavic, Michael A.,Combrink, Keith D.,Takusagawa, Fusao
, p. 5810 - 5812 (2007/10/02)
7-Aryl-3-hydroxy-6-methylbicyclooct-3-ene-2,8-diones 4 and 8 are formed exclusively in Ti(IV)-catalyzed reactions of 2-((4-methoxybenzyl)oxy)-1,4-benzoquinones 5a/d with trans-β-methylstyrene and indene, resprectively.
