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Synthesis 2010(1): 141-152  
DOI: 10.1055/s-0029-1217048
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Tandem Reactions of 2-Methylimidazoline and 1,2-Dimethylimidazoline with Various Benzoyl Chlorides

Guozhong Ye*a, Chunlong Chenb, Sabornie Chatterjeea, Willard E. Colliera, Aihua Zhouc, Yingquan Songa, Debbie J. Bearda, Charles U. Jr. Pittman *a
a Department of Chemistry, Mississippi State University, Starkville, MS 39762, USA
Fax: +1(662)3257611; e-Mail: cpittman@chemistry.msstate.edu; e-Mail: gye001@gmail.com;
b Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
c Pharmacy School, University of Wisconsin-Madison, Madison, WI 53706, USA
Further Information

Publication History

Received 19 July 2009
Publication Date:
19 October 2009 (online)

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Abstract

The reactions of 2-methylimidazoline with excess benzoyl chlorides under mild conditions generated N,N′-diacyl-β-keto cyclic ketene-N,N′-acetals. Conversely, the corresponding reactions of 1,2-dimethylimidazoline under the same conditions stereoselectively formed the ring-opened (Z)-vinyl benzoates. The latter reactions feature the formation of carbon-carbon bonds, carbon-nitrogen bonds, and carbon-oxygen bonds in one sequential cascade.

Key words

acyl ketene-N,N′-acetal - carbon-carbon bond formation - 2-methylimidazoline - 1,2-dimethylimidazoline

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X-ray crystallographic description of 12a: Crystal dimensions (mm): 0.38 × 0.35 × 0.22. C26H25.5N2O4.25; Mr = 433.98. Triclinic; space group P1; a = 8.571(2) Å, b = 10.140(2) Å, c = 14.383(3) Å; α = 103.687(3)˚, β = 106.909(3)˚, γ = 96.759(4)˚; V = 1138.5(4) ų; Z = 2; D(calcd) = 1.266 g/cm³; µ (mm-¹) = 0.086; F(000) = 459; Reflections collected/unique = 8421/4000; refinement method: full-matrix least-squares on F ²; final R indices [I > 2s (I)]. R1 = 0.0468, wR2 = 0.1099, R indices (all data) R1 = 0.1093, wR2 = 0.1370; goodness of fit on F² = 1.000. Crystals were grown by slow evaporization of pentane into a CHCl3-EtOAc solution of 12a. CCDC number for compound 12a is CCDC 683239. This data can be obtained free of charge from the Cambridge Crystallographic Data Centre via ww.ccdc.cam.ac.uk/datarequest/cif.

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SMART Version 5.625, SAINT+Version 6.22, 2001. Bruker Analytical X-ray Systems, Inc., Madison, Wisconsin, USA.

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G. M. Sheldrick; SHELXTL Version 6.1, 2000; Bruker Analytical X-ray Systems, Inc., Madison, Wisconsin, USA.