510-80-5Relevant academic research and scientific papers
The Titanium-Mediated Double Reductive Cleavage of Cyclic Sulfonamides for the Synthesis of Aryl Pyrrolidines
Khalifa, Aisha,Evans, Paul
, p. 2969 - 2975 (2019/02/26)
Reduction of a range of benzo-fused cyclic sulfonamides has been accomplished using low-valent titanium. This operationally simple method generates the corresponding aryl-substituted cyclic amines, typically, with good conversion. Notably, unlike our previous Li-NH3-based method, loss of heteroatom-based substituents (X) on the aromatic ring does not readily occur, and the robustness of this method was demonstrated with a synthesis of the Sceletium alkaloid mesembrane.
Concise Total Syntheses of (±)-Joubertiamine, (±)- O -Methyljoubertiamine, (±)-3′-Methoxy-4′- O -methyljoubertiamine, (±)-Mesembrane, and (±)-Crinane
Das, Mrinal Kanti,De, Subhadip,Bisai, Alakesh
, p. 2093 - 2104 (2016/07/06)
A method to access cis-3a-aryloctahydroindole alkaloids has been developed through a key strategy involving Eschenmoser-Claisen rearrangement of allylalcohol. This approach gives us an opportunity to access the all-carbon quaternary center required for ci
Concise total syntheses of (±)-mesembrane and (±)-crinane
Das, Mrinal Kanti,De, Subhadip,Shubhashish,Bisai, Alakesh
, p. 3585 - 3588 (2015/03/30)
A straightforward and unified strategy to access Amaryllidaceae alkaloids comprising a cis-3a-aryloctahydroindole scaffold has been developed. The strategy features Eschenmoser-Claisen rearrangement of allylalcohol as a key step for the installation of al
Selective generation of quaternary all-carbon-centres through Heck-cyclisations: Synthesis of mesembrane
Klein, Johannes E. M. N.,Geoghegan, Kimberly,Meral, Nicolas,Evans, Paul
supporting information; experimental part, p. 937 - 939 (2010/06/12)
Described is an observation that the intramolecular Heck reaction of a trisubstituted alkene proceeds with high regioselectivity and leads to the preferential formation of a quaternary all-carbon-centre. This observation was subsequently applied in a short synthesis of (±)-mesembrane. The Royal Society of Chemistry 2010.
Stereoselective synthesis of cis and trans-fused 3a-aryloctahydroindoles using cyclization of N-vinylic α-(methylthio)acetamides: synthesis of (-)-mesembrane
Saito, Miho,Matsuo, Jun-ichi,Ishibashi, Hiroyuki
, p. 4865 - 4873 (2008/02/01)
Treatment of N-(2-arylcyclohex-1-en-1-yl)-α-(methylthio)acetamides with N-chlorosuccinimide (NCS) gave 3a-aryl-2,3,3a,4,5,6-hexahydro-3-(methylthio)indol-2-ones. Desulfurization of the cyclization products followed by a catalytic hydrogenation of the resu
Application of furanyl carbamate cycloadditions toward the synthesis of hexahydroindolinone alkaloids
Padwa,Brodney,Dimitroff,Liu,Wu
, p. 3119 - 3128 (2007/10/03)
A convenient synthesis of various substituted hexahydroindolinones has been achieved by an intramolecular Diels-Alder cycloaddition reaction (IMDAF) of furanyl carbamates bearing tethered alkenyl groups. 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. A synthetic route to (±)-mesembrane and (±)-crinane was accomplished using this methodology. It was possible to carry out a stereoselective reduction of the initially formed hexahydroindolinone ring to produce the cis-3a-aryl-hydroindole skeleton. A related [4 + 2]-cycloaddition/rearrangement sequence was also used for a formal synthesis of the Chinese ornamental orchid (±)-dendrobine. The tricyclic alkaloid core was formed stereoselectivity from the thermolysis of N-[(2-methyl-2-cyclopentenyl)methyl]-N-(4-isopropyl-furan-2-yl)carbamic acid tert-butyl ester. Kende's advanced intermediate 33 was prepared in seven additional steps by standard transformations, thereby completing a formal synthesis of (±)-dendrobine.
Total syntheses of (-)-mesembrane and (-)-mesembrine via palladium-catalyzed enantioselective allylic substitution and zirconium-promoted cyclization
Mori,Kuroda,Zhang,Sato
, p. 3263 - 3270 (2007/10/03)
4-Arylhexahydroindole derivatives 5 were synthesized from 2-arylcyclohexenyl allylamine derivatives 4, which have a large protecting group on nitrogen, using zirconium-promoted cyclization. Reaction of 4e with Cp2ZrBu2, followed by treatment with MeMgBr and then O2, gave 2a in 63% yield by a one-pot reaction, since the approach of O2 to zirconium was prevented by the aryl group. The total syntheses of (+)-mesembrane and (+)-mesembrine were achieved starting from 2a. To synthesize these natural products in a chiral form, the starting allylamine derivative 24 (80% yield, 86% ee, recrystallized from MeOH, 99% ee with 79% recovery) was prepared from allyl carbonate 22a and N-tosylallylamine 23 using palladium-catalyzed asymmetric amination in the presence of (S)-BINAPO as a chiral ligand. (-)-Mesembrane and (-)-mesembrine were synthesized from this allylamine 24.
Generation of 2-azaallyl anions by the transmetalation of N-(trialkylstannyl)methanimines. Pyrrolidine synthesis by [3 + 2] cycloadditions with alkenes
Pearson, William H.,Szura, Daniel P.,Postich, Michael J.
, p. 1329 - 1345 (2007/10/02)
Treatment of N-(trimethylstannyl)methanimines or N-(tri-n-butylstannyl)methanimines with methyllithium or n-butyllithium, respectively, affords 2-azaallyl anions by tin-lithium exchange. These anions undergo intermolecular or intramolecular [π4s + π2s] cycloadditions with alkenes and alkynes to generate pyrrolidines or pyrrolines after quenching with water or other electrophiles. The tin-lithium exchange method allows unstabilized 2-azaallyl anions to be generated for the first time. The lifetime of the anions is limited by a competing intermolecular side reaction. Therefore, relatively reactive alkenes and alkynes must be used, such as stilbene, styrenes, enynes, diphenylacetylene, vinyl sulfides, vinyl selenides, and vinyl silanes. The latter three types of anionophiles afford functionalized cycloadducts which may be transformed into more useful pyrrolidines by reduction, elimination, or oxidation. A synthesis of the alkaloid (±)-mesembrane was accomplished using an intramolecular 2-azaallyl anion cycloaddition.
Stereoselective Preparation of Bicyclic Lactams by Copper- or Ruthenium-catalysed Cyclization of N-Allyltrichloroacetamides: A Novel Entry to Pyrrolidine Alkaloid Skeletons
Nagashima, Hideo,Ara, Ken-ichi,Wakamatsu, Hidetoshi,Itoh, Kenji
, p. 518 - 519 (2007/10/02)
Cyclization of certain N-allyltrichloroacetamides provides a stereoselective preparative method for several bicyclic lactams.
