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Synthesis of 3-pyrrolines

Recent Literature

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.

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.

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.

The use of cationic silver (AgSbF₄) as a catalyst for intra- and intermolecular alkyne-carbonyl coupling is described.
J. U. Rhee, M. J. Krische, Org. Lett., 2005, 7, 2493-2495.

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.