A new approach to substituted cyclobutanes: Direct β-deprotonation/magnesiation of cyclobutane carboxamides

Synlett

Volumn , Issue 9 SPEC. ISS., 2003, Pages 1275-1278

  Eaton, Philip E ^a   Zhang, Mao Xi ^a   Komiya, Naruyoshi ^a   Yang, Cai Guang ^a   Steele, Ian ^a   Gilardi, Richard ^b  

^a UNIVERSITY OF CHICAGO   (United States)

^b NAVAL RESEARCH LABORATORY   (United States)

Author keywords

Amido Grignards; Cyclobutanes; Diastereoselective; Metalation; Substituent effects

Indexed keywords

AMIDE; CYCLOBUTANE DERIVATIVE; MAGNESIUM DERIVATIVE; NITROGEN DERIVATIVE; REAGENT;

ARTICLE; CARBOXYLATION; CHEMICAL REACTION; CHEMICAL REACTION KINETICS; CHEMICAL STRUCTURE; DEPROTONATION; DIASTEREOISOMER; ESTERIFICATION; GRIGNARD REACTION; MAGNESIATION; MOLECULAR STABILITY; PROTON TRANSPORT; REACTION ANALYSIS; STEREOCHEMISTRY; STOICHIOMETRY; SUBSTITUTION REACTION; SYNTHESIS; TECHNIQUE; THERMODYNAMICS;

EID: 0038780847     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-2003-40331     Document Type: Article

References (13)

1. (a) Eaton, P. E.; Zhang, M. X. Angew. Chem. Int. Ed.; 2002, 41, 2169.
2. (b) See also: Eaton, P. E.; Lee, C. H.; Xiong, Y. J. Am. Chem. Soc. 1989, 111, 8016.
3. (c) Eaton, P. E.; Xiong, Y.; Lee, C. H. J. Chin. Chem. Soc. 1991, 38, 303.
4. The activating/stabilizing carboxamido group need not be on the β-carbon, see: Eaton, P. E.; Lukin, K. J. Am. Chem. Soc. 1993, 115, 11370.
5. Streitwieser, A. Jr.; Caldwell, R. A.; Young, W. R. J. Am. Chem. Soc. 1969, 91, 529.
6. We assign the liganding interaction shown by analogy to that seen in a cyclopropyl example for which we have a single crystal X-ray structure: Eaton, P. E.; Zhang, M. X.; Steele, I., unpublished results
7. 13C NMR (100 MHz): δ = 173.2, 52.0, 48.3, 46.1, 30.8, 30.2, 29.2, 22.2, 21.6, 21.1, 20.5, 20.2. MS (ES): 324.0 [M + 1].
8. Crystallographic data have been deposited with the Cambridge Crystallographic Data Centre, e-mail: deposit@ccde.cam.ac.uk, as supplementary publications numbered: (a) 206444; (b) 173571; (c) 209582 (racemate); (d) 205769.
9. +}. See: Gawley, R. E. In Grignard Reagents. New Developments; Richey, H. G. Jr., Ed.; Wiley: Chichester, 2000, 139.
10. We estimate that we would have seen in the NMR spectra of the crudes any other isomer present in >10% yield.
11. 2 and sec-BuMgN(i-Pr). We have made each separately and have found only small differences in their ability to deprotonate/ magnesiate 3.
12. Zhang, M. X.; Komiya, N.; Eaton, P. E. 224th ACS National Meeting, Boston; 2002, 341-ORGN.
13. Best value at present for neopentane:cyclohexane relative kinetic acidity is 8.2:1 (per hydrogen) obtained using CsCHA at 50°C. Private Communication, Prof. A. Streitwieser, March 4, 2003.