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DOI: 10.1055/s-0030-1259680
Intramolecular Hydroamination of Conjugated Dienes Catalyzed by Lewis and Brønsted Acids
Publikationsverlauf
Publikationsdatum:
22. Februar 2011 (online)
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Abstract
Intramolecular hydroaminations of conjugated acyclic aminodienes catalyzed by Lewis acids such as silver triflate, cationic gold complexes, BINAP-copper(II) triflate, iron trichloride, indium(III) bromide, iodine and by TfOH, as a representative Brønsted acid, are evaluated. The reaction proceeds in a 1,4-addition manner through a 5-exo-trig cyclization affording the corresponding 2-substituted pyrrolidines, (triphenylphosphite)gold(I) triflate, and TfOH providing the best results.
Key words
hydroamination - conjugated dienes - Lewis acids - triflic acid - sulfonamides
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References and Notes
Substrates 1a-c and 2 were synthesized according to Muñiz et al. (ref. 2c) in a slightly modified route. For the synthesis of 1d, see ref. 6.
16Other authors described the fomation of 2-allyl pyrrolidine as a minor product.²a,³,5
18Reactions catalyzed by AgOTf and [(PhO)3P]AuOTf were carried out with light exclusion. (±)-BINAP-Cu(OTf)2 complex was formed in situ by mixing equimolar amounts of (±)-BINAP and Cu(OTf)2 for 15 min at the reaction temperature.
19For hydroamination reactions catalyzed by FeCl3˙6H2O, an argon atmosphere was not necessary and HPLC grade DCE was used as solvent.