Synlett 2014; 25(16): 2271-2274
DOI: 10.1055/s-0034-1378362
cluster
© Georg Thieme Verlag Stuttgart · New York

1,4-Diazabicyclo[2.2.2]octane-Mediated Ring Opening of 1-Acetylcyclopropanecarboxamides and Its Application to the Construction of 3-Alkylated γ-Lactams

Ling Li
a   Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China   Fax: +86(431)85099759   eMail: liangfs112@nenu.edu.cn
,
Enxiang Wei
a   Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China   Fax: +86(431)85099759   eMail: liangfs112@nenu.edu.cn
,
Shaoxia Lin
a   Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China   Fax: +86(431)85099759   eMail: liangfs112@nenu.edu.cn
,
Bing Liu
a   Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China   Fax: +86(431)85099759   eMail: liangfs112@nenu.edu.cn
,
Fushun Liang*
a   Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China   Fax: +86(431)85099759   eMail: liangfs112@nenu.edu.cn
b   Key Laboratory for UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, P. R. of China
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Publikationsverlauf

Received: 10. Mai 2014

Accepted after revision: 09. Juni 2014

Publikationsdatum:
28. Juli 2014 (online)


Abstract

1,4-Diazabicyclo[2.2.2]octane (DABCO)-mediated ring opening of 1-acetylcyclopropanecarboxamides efficiently gave stable zwitterions that could be formed in situ or readily isolated. An application of this novel type of ring opening was demonstrated in a one-pot efficient construction of biologically interesting 3-alkyl γ-lactams. The Lewis-base protocol provides an opportunity for performing ring opening, cycloaddition, and rearrangement reactions of donor–acceptor cyclopropanes through organocatalysis.

Supporting Information

 
  • References and Notes


    • For Lewis base mediated ring-opening of cyclopropanes, see:
    • 3a Danishefsky S, Singh RK. J. Am. Chem. Soc. 1975; 97: 3239
    • 3b Budynina EM, Ivanova OA, Averina EB, Kuznetsova TS, Zefirov NS. Tetrahedron Lett. 2006; 47: 647
    • 3c In their research, Wang and co-workers proposed nucleophilic addition of DABCO as a mechanism for cyclopropane ring opening, see: Du D, Wang Z. Tetrahedron Lett. 2008; 49: 956
  • 8 (2Z)-3-(Anilinocarbonyl)-5-(4-aza-1-azoniabicyclo-[2.2.2]oct-1-yl)pent-2-en-2-olate (2a); Typical Procedure DABCO (156 mg, 1.05 equiv) was added to a solution of cyclopropane 1a (102 mg, 0.5 mmol) in H2O (1.0 mL), and the mixture was stirred at 60 °C for 12 h. The mixture was then cooled to r.t., and H2O was removed under reduced pressure to give a white solid. The crude product was washed with MeOH and EtOAc (×3), and dried under ambient conditions to give a white solid; yield: 150 mg (95%); mp 173–175 °C; 1H NMR (500 MHz, D2O): δ = 1.75–1.76 (d, J = 7.5 Hz, 3 H), 2.32–2.35 (t, J = 8.0 Hz, 2 H), 2.72–2.75 (t, J = 8.5 Hz, 2 H), 2.79–2.80 (d, J = 6.5 Hz, 6 H), 3.01–3.02 (d, J = 6.5 Hz, 6 H), 6.83–6.86 (t, J = 7.0 Hz, 1 H), 7.11–7.14 (t, J = 8.0 Hz, 2 H), 7.25–7.26 (d, J = 8.0 Hz, 2 H); 13C NMR (125 MHz, D2O): δ = 20.4, 24.1, 44.2, 51.8, 63.7, 93.2, 119.9, 123.1, 129.5, 139.6, 170.0, 181.4; HRMS (ESI-TOF): m/z [M + H] calcd for C18H26N3O2: 316.2025; found: 316.2021.
  • 9 The reason for this is still unclear.
  • 11 3-Acetyl-3-methyl-1-phenylpyrrolidin-2-one (3a); Typical Procedure DABCO (156 mg, 1.05 equiv) was added to a solution of cyclopropane 1a (102 mg, 0.5 mmol) in MeCN (1.0 mL), and the mixture was stirred at 60 °C for 12 h. The mixture was then cooled to r.t., and MeCN was removed under reduced pressure. A solution of MeI (0.047mL, 1.5 equiv) in DMF (2.0 mL) was added, and the mixture was stirred at r.t. for 30 min. Finally, NaOH (240 mg, 1.2 equiv) was added, and the mixture was stirred for 30 min. The mixture was poured into brine (10 mL) and extracted with EtOAc (3 × 10 mL). The organic phases were combined, washed with H2O (3 × 10 mL), dried (MgSO4), filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography (PE–Et2O) to give colorless crystals; yield: 94.5 mg (87%); mp 86–88 °C; 1H NMR (500 MHz, CDCl3): δ = 1.55 (s, 3 H), 1.84–1.90 (m, 1 H), 2.33 (s, 3 H), 2.81–2.85 (m, 1 H), 3.71–3.75 (m, 1 H), 3.75–3.87 (m, 1 H), 7.16 (t, J = 7.0 Hz, 1 H), 7.49 (t, J = 7.5 Hz, 2 H), 7.63 (t, J = 7.5 Hz, 2 H); 13C NMR (125 MHz, CDCl3): δ = 21.2, 26.0, 28.6, 45.8, 59.6, 119.8, 124.9, 128.8, 139.1, 172.4, 205.8; HRMS (ESI-TOF): m/z [M + H] calcd for C13H16NO2: 218.1181; found: 218.1192.