114879-09-3Relevant articles and documents
The cobalt-mediated [2+2+2] cycloaddition of α,ω-diynes to the 2,3-double bond of indole
Boese,Van Sickle,Vollhardt
, p. 1374 - 1382 (1994)
The reaction of acetyl or phenylsulfonylindole with α,ω-diynes and CpCo(C2H4)2 yields CpCo-complexed dihydrocarbazoles. 1-Trimethylsilyl-1,6-heptadiyne gives an adduct in which the silyl moiety is distal to the phenylsulfonamide. 1-Trimethylsilyl-1,7-octadiyne results in an unusual diene complex resulting from C-H activation at C-2 of the indole. The behavior of a number of terminally substituted 4-aza, 1,7-octadiynes to the reaction is investigated. The oxidation of one dihydrocarbazole complex with triphenylcarbenium hexafluorophosphate or with Fe(NO3)3 furnishes an η5-cyclohexadienyl cobalt complex and its subsequent conversion into substituted diene complexes or to the demetallated carbazole is discussed.
Strictosidine synthase: Mechanism of a Pictet-Spengler catalyzing enzyme
Maresh, Justin J.,Giddings, Lesley-Ann,Friedrich, Anne,Loris, Elke A.,Panjikar, Santosh,Trout, Bernhardt L.,Stoeckigt, Joachim,Peters, Baron,O'Connor, Sarah E.
, p. 710 - 723 (2008)
The Pictet-Spengler reaction, which yields either a β-carboline or a tetrahydroquinoline product from an aromatic amine and an aldehyde, is widely utilized in plant alkaloid biosynthesis. Here we deconvolute the role that the biosynthetic enzyme strictosidine synthase plays in catalyzing the stereoselective synthesis of a β-carboline product. Notably, the rate-controlling step of the enzyme mechanism, as identified by the appearance of a primary kinetic isotope effect (KIE), is the rearomatization of a positively charged intermediate. The KIE of a nonenzymatic Pictet-Spengler reaction indicates that rearomatization is also rate-controlling in solution, suggesting that the enzyme does not significantly change the mechanism of the reaction. Additionally, the pH dependence of the solution and enzymatic reactions provides evidence for a sequence of acid-base catalysis steps that catalyze the Pictet-Spengler reaction. An additional acid-catalyzed step, most likely protonation of a carbinolamine intermediate, is also significantly rate controlling. We propose that this step is efficiently catalyzed by the enzyme. Structural analysis of a bisubstrate inhibitor bound to the enzyme suggests that the active site is exquisitely tuned to correctly orient the iminium intermediate for productive cyclization to form the diastereoselective product. Furthermore, ab initio calculations suggest the structures of possible productive transition states involved in the mechanism. Importantly, these calculations suggest that a spiroindolenine intermediate, often invoked in the Pictet-Spengler mechanism, does not occur. A detailed mechanism for enzymatic catalysis of the β-carboline product is proposed from these data.
Electrophilic Substitution in Indoles. Part 13. The Synthesis and Rearrangement of 2-Deuteriospiro
Ibaceta-Lizana, Juana S. L.,Jackson, Anthony H.,Prasitpan, Noojare,Shannon, Patrick V. R.
, p. 1221 - 1226 (1987)
2-Deuterioindole was prepared from N-phenylsulphonylindole by lithiation, quenching with D2O, and hydrolysis.Treatment of the 2-deuterioindole Grignard reagent with succinic anhydride gave 4-(indol-3-yl)-4-oxobutanoic acid with partial loss of the deuterium from the 2-position. 2,3-Dideuterioindole (prepared by acid-catalysed deuteration of 2-deuterioindole) when treated in the same way, gave the indolyl oxobutanoic acid, 92 percent deuteriated at the indolyl 2-position.Reduction to the deuterioindolylbutanol and treatment of its toluene-p-sulphonate with potassium t-butoxide give 2-deuterio-spiro which was 88 percent deuteriated at the 2-position.The kinetics of the acid-catalysed rearrangement of the deuterioindolenine and its non-deuteriated analogue were measured and the ratio kH/kD of the pseudo-first-order rate constants was found to be 1.08, showing that the isotope effect was very small.
Chemospecific Cyclizations of α-Carbonyl Sulfoxonium Ylides on Aryls and Heteroaryls
Clare, Daniel,Dobson, Benjamin C.,Inglesby, Phillip A.,A?ssa, Christophe
supporting information, p. 16198 - 16202 (2019/11/03)
The functionalization of aryl and heteroaryls using α-carbonyl sulfoxonium ylides without the help of a directing group has remained so far a neglected area, despite the advantageous safety profile of sulfoxonium ylides. Described herein are the cyclizations of α-carbonyl sulfoxonium ylides onto benzenes, benzofurans and N-p-toluenesulfonyl indoles in the presence of a base in HFIP, whereas pyrroles and N-methyl indoles undergo cyclization in the presence of an iridium catalyst. Significantly, these two sets of conditions are chemospecific for each groups of substrates.
Manganese-catalyzed synthesis of monofluoroalkenes: Via C-H activation and C-F cleavage
Cai, Sai-Hu,Ye, Lu,Wang, Ding-Xing,Wang, Yi-Qiu,Lai, Lin-Jie,Zhu, Chuan,Feng, Chao,Loh, Teck-Peng
supporting information, p. 8731 - 8734 (2017/08/09)
The manganese-catalyzed α-fluoroalkenylation of arenes via C-H activation and C-F cleavage has been described. This protocol provides a very useful method for the synthesis of monofluoroalkenes with predominant unconventional E-isomer selectivity which complements the existing strategies for the access to these molecular architectures. In addition, the selectivity of β-defluorination in the catalytic cycle not only determines the configurations of the products but also obviates the use of external oxidants, providing a good example in the exploitation of manganese-catalyzed redox-neutral C-H transformations.
Rhodium(II)-catalyzed intramolecular annulation of 1-sulfonyl-1,2,3- triazoles with pyrrole and indole rings: Facile synthesis of N-bridgehead azepine skeletons
Yang, Jin-Ming,Zhu, Cheng-Zhi,Tang, Xiang-Ying,Shi, Min
supporting information, p. 5142 - 5146 (2014/05/20)
A convenient and efficient synthetic method has been developed to construct highly functionalized N-bridgehead azepine skeletons, which are of great importance in biological and pharmaceutical industry. The reaction proceeds through a rhodium(II) azavinyl carbene intermediate, which initiated the intramolecular C-H functionalization with pyrrolyl and indolyl rings. A variety of azepine derivatives were obtained in moderate to good yields under mild reaction conditions with high chemoselectivity. Several interesting derivatizations of the resulting products demonstrate that this method is synthetically valuable and useful. Heads up: A convenient and efficient synthetic method of highly functionalized N-bridgehead azepine skeletons was developed using a rhodium(II)-catalyzed intramolecular annulation of pyrrolyl and indolyl triazoles. Several interesting transformations of the products into poly-heterocyclic products and the reaction mechanism are disclosed. Ts=4-toluenesulfonyl.
Rhodium(I)-catalyzed cycloisomerization of nitrogen-tethered indoles and alkylidenecyclopropanes: Convenient access to polycyclic indole derivatives
Zhang, Di-Han,Tang, Xiang-Ying,Wei, Yin,Shi, Min
supporting information, p. 13668 - 13673 (2013/10/22)
At the end of its tether: A new synthetic protocol for the preparation of polycyclic indole derivatives has been developed from a rhodium(I)-catalyzed cycloisomerization of a nitrogen-tethered indole and alkylidenecyclopropane, affording the corresponding
