Categories: Synthesis of N-Heterocycles >
Synthesis of 3-pyrrolines
3-Pyrroline has been prepared from (Z)-1,4-dichloro-2-butene in three steps in an overall yield of 74%. The Delépine Reaction permitted the monoamination of the substrate in practically quantitative yields. The subsequent ring-closing reaction was less efficient.
S. Brandänge, B. Rodriquez, Synthesis, 1988, 347-348.
Grubbs second generation ruthenium catalyst catalyzes various ring closing metathesis and hydrosilylation reactions in aqueous medium. Reactions proceeded in pure water without any additives or cosolvents, in a short period of time. We found that inhomogeneity of the reaction mixture does not prevent high conversion of the products in both reactions.
V. Polshettiwar, R. S. Varma, J. Org. Chem., 2008, 73, 7417-7419.
In an asymmetric intermolecular Heck reaction, various cyclic olefins coupled with aryl and vinyl bromides in high enantioselectivity. Only bisphosphine oxides on a spiro backbone formed highly stereoselective Pd catalysts. The use of alkylammonium salts and alcoholic solvents were essential to promote halide dissociation from the arylpalladium intermediate.
C. Wu, J. Zhou, J. Am. Chem. Soc., 2014, 136, 650-652.
Ring-expansion transformations of vinyl aziridines are widely used to give various medium or larger N-heterocycles of synthetic interest. (CuOTf)2·toluene catalyzes a ring expansion of vinyl aziridines to 3-pyrrolines under mild conditions (THF, rt).
E. Tosi, K. Spielmann, R. M. de Figueiredo, J.-M. Campagne, Synlett, 2021, 32, 517-520.
An efficient alkene aza-Cope-Mannich cyclization between 2-hydroxy homoallyl tosylamine and aldehydes in the presence of iron(III) salts gives 3-alkyl-1-tosyl pyrrolidines in good yields via a γ-unsaturated iminium ion, 2-azonia-[3,3]-sigmatropic rearrangement, and intramolecular Mannich reaction. The cyclization of 2-hydroxy homopropargyl tosylamines gives dihydro-1H-pyrroles.
R. M. Carballo, M. Purino, M. A. Ramírez, V. S. Martín, J. I. Padrón, Org. Lett., 2010, 12, 5334-5337.
A phosphine-catalyzed annulation of modified allylic ylides with various aromatic imines gives 3-pyrrolines in moderate to very good yield. The presence of a substituent (R) in the allylic compound is crucial for this reaction.
S. Zheng, X. Lu, Org. Lett., 2008, 10, 4481-4484.
Synthesis of various highly functionalized Δ3-pyrrolines has been accomplished by a AgNO3-catalyzed cyclization reaction of allenic amino acids that proceeds with transfer of chiral information. A new mode of cyclization of allenic benzoyl-protected amines in the Ag(I)-catalyzed reaction leading to oxazines was also observed.
B. Mitasev, K. M. Brummond, Synlett, 2006, 3100-3104.
Treatment of α-amino allenes bearing a protected amino group with potassium carbonate in DMF under reflux in the absence of any transition-metal catalysts gave the corresponding 3-pyrrolines in good to excellent yields, by 5-endo-trig mode cycloisomerization in a stereoselective manner.
H. Ohno, Y. Kadoh, N. Fujii, T. Tanaka, Org. Lett., 2006, 8, 947-950.
Enantioenriched propargyl mesylates or perfluorobenzoates react with α-(N-carbamoyl)alkylcuprates to afford scalemic α-(N-carbamoyl) allenes. Subsequent N-Boc deprotection and AgNO3-promoted cyclization afford enantioenriched N-alkyl-3-pyrrolines.
R. K. Dieter, N. Chen, V. K. Gore, J. Org. Chem., 2006, 71, 8755-8760.
A wide screening of substrates in ring-closing metathesis reactions reveals the great efficiency of phosphabicyclononane (phoban)-containing ruthenium-based pre-catalysts. Comparison of the catalytic activities with Grubbs' first-generation pre-catalyst illustrates the key role of the Phoban ligand.
F. Boeda, H. Clavier, M. Jordaan, W. H. Meyer, S. P. Nolan, J. Org. Chem., 2008, 73, 259-263.
Δ3-Aryl/heteroaryl substituted heterocycles via sequential Pd-catalysed termolecular cascade/ring closing metathesis (RCM)
H. A. Dondas, B. Clique, B. Cetinkaya, R. Grigg, C. Kilner, J. Morris, V. Sridharan, Tetrahedron, 2005, 61, 10652-10666.
A series of new pyrrolidine derivatives were prepared directly in very good yields, from substrates containing a basic or nucleophilic N atom via ring-closing enyne metathesis reaction under mild reaction conditions.
Q. Yang, H. Alper, W.-J Xiao, Org. Lett., 2007, 9, 769-771.
1,3,4-triaryl-2,5-dihydropyrroles were synthesized using the McMurry coupling reaction as key step. A facile and reliable non-catalytic photoconversion of 1,3,4-triaryl-2,5-dihydropyrroles furnished 1,3,4-triarylpyrroles in good yields.
D. X. Zeng, Y. Chen, Synlett, 2006, 490-492.
Allenylidene-ruthenium complexes on protonation with HOTf are rearranged to indenylidene-ruthenium complexes, which are efficient catalyst precursors for ring-opening metathesis polymerization, ring-closing metathesis and enyne metathesis of a variety of substrates.
R. Castarlenas, C. Vovard, C. Fischmeister, P. H. Dixneuf, J. Am. Chem. Soc., 2006, 128, 4079-4089.
An intramolecular chloroamination of allenes with N-chlorosuccinimide proceeds under mild conditions in the presence of a 1,10-phenanthroline-ligated cationic silver complex and 2,6-lutidine as a base. The reaction tolerates various functional groups. The chloroamination products are useful synthetic intermediates and can be easily transformed into functionalized 3-pyrroline and pyrrole derivatives.
M. Sai, S. Matsubara, Org. Lett., 2011, 13, 4676-4679.
A reaction between dialkyl acetylenedicarboxylates and β-aminoketones promoted by triphenylphosphine allows an efficient one-pot synthesis of polysubstituted 2,5-dihydropyrrole derivatives. The prepared 2,5-dihydropyrroles can be easily oxidized to the corresponding pyrrole derivatives with chromium trioxide.
M. Anary-Abbasinejad, E. Poorhassan, A. Hassanabadi, Synlett, 2009, 1929-1932.
The reaction of alkynyl ketones with N-tosylimines catalyzed by Bu3P at room temperature in toluene gives highly functionalized 3-pyrrolines in very good yields. When DMAP was used in place of Bu3P as catalyst to facilitate the cycloaddition, completely substituted azetidines were produced in moderate yields in CH2Cl2.
L-G. Meng, P. Cai, Q. Guo, S. Xue, J. Org. Chem., 2008, 73, 8491-8496.
The reduction of various hetero- and carbocyclic aromatic compounds under ammonia free conditions uses LiDBB as a source of electrons, bis(methoxyethyl)amine (BMEA) as a protonating agent, and THF as a solvent. In contrast to Birch type conditions, the described ammonia free conditions allow the use of reactive electrophiles.
T. J. Donohoe, D. House, J. Org. Chem., 2002, 67, 5015-5018.