Stereoselective [2 + 2 + 2] cocyclotrimerization of oxa- and azabenzonorbornadienes † with alkynes catalyzed by nickel complexes: first transition metal-mediated synthesis of isobenzofuran and isoindole precursors
作者:Thota Sambaiah、Daw-Jen Huang、Chien-Hong Cheng
DOI:10.1039/a907654i
日期:——
are convenient isobenzofuran and isoindole precursors that react with various dienophiles to afford the corresponding Diels–Alder adducts. In addition, the [2 + 2 + 2] cycloadducts may be used as precursors for the synthesis of aromatic compounds. For example, the reaction of 1a with methyl but-2-ynoate catalyzed by the nickel system provided aromatic compound 3 in 94% yield. In this reaction, 1a is
Benzylic Functionalization of Anthrones via the Asymmetric Ring Opening of Oxabicycles Utilizing a Fourth‐Generation Rhodium Catalytic System
作者:Charles C. J. Loh、Xiang Fang、Brendan Peters、Mark Lautens
DOI:10.1002/chem.201502718
日期:2015.9.28
with no asymmetrictransitionmetal catalyzed example to date. Herein, we report the first asymmetrictransitionmetal catalyzed benzylic functionalization of anthrones through the rhodium(I) catalyzed desymmetrization of oxabicycles. As previously developed rhodium(I) systems were found to be unsuitable for this substrate, a new robust fourth‐generation [Rh(cod)OH]2 based catalyticsystem was developed
Chromium-Catalyzed <i>syn</i>-Selective Ring-Opening Aryl-/Alkylation of 7-Oxabenzonorbornadiene Derivatives with Grignard Reagents
作者:Kohei Nishi、Hayato Tsurugi、Kazushi Mashima
DOI:10.1021/acscatal.2c05029
日期:2023.3.3
arylchromium species such as neutral triarylchromium(III) and anionic tetraarylchromate(III) suggested that in situ formed diarylchromate(I) from tetraarylchromate(III) served as the active species in this catalytic reaction. The magnetic susceptibility of the in situ generated chromium species from CrCl3(thf)3 and excess amounts of p-tolylmagnesium bromide was reasonable for the low-spin Cr(I) species (μ =
Ruthenium-Catalyzed Nucleophilic Ring-Opening Reactions of 7-Oxabenzonorbornadienes with Methanol
作者:Kelsey Jack、Elisabeth Fatila、Colleen Hillis、William Tam
DOI:10.1080/00397911.2011.626140
日期:2013.4.18
Ruthenium-catalyzed nucleophilic ring-opening reaction of 7-oxabenzonorbornadienes with methanol was investigated. Among various ruthenium catalysts tested, Cp* Ru (COD)Cl gave the greatest yields in the ring-opening reaction. The reactions were found to be highly stereoselective, giving only the anti-ring-opening products in moderate yields. Both symmetrical and unsymmetrical 7-oxabenzonorbornadienes were employed in the study, and moderate to excellent regioselectivities were observed.Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) to view the free supplemental file.
Practical Asymmetric Synthesis of Bioactive Aminotetralins from a Racemic Precursor Using a Regiodivergent Resolution
作者:Robert Webster、Alistair Boyer、Matthew J. Fleming、Mark Lautens
DOI:10.1021/ol1022239
日期:2010.12.3
Catalyst-controlled asymmetric ring opening of a racemic oxabicyclic alkene leads to two readily separable regioisomeric products both in excellent ee. A cationic Rh catalyst, with added NH4BF4 to modulate reactivity, was required to obtain synthetically useful yields. The utility of each substituted aminotetralin product has been demonstrated by their conversion to different biologically relevant