Direct alkylation of α-substituted aldehydes

Journal of Organic Chemistry

Volumn 61, Issue 26, 1996, Pages 9076-9077

  Valenta, Zdenek ^a   MaGee, David I ^a   Setiadji, Santosa ^a  

^a UNIVERSITY OF NEW BRUNSWICK   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0343820008     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo9614710     Document Type: Article

References (14)

1. For a review, see: Caine, D. In Carbon-Carbon Bond Formation; Augustine, R. L., Ed.; Marcel Dekker: New York, 1979; Chapter 2.
2. Groenoewegen, P.; Kallenberg, H.; van der Gen, A. Tetrahedron Lett. 1978, 5, 491.
3. Artaud, I.; Torrosian, G.; Viout, P. Tetrahedron 1985, 41, 5031.
4. For a discussion of "closed" (metal mediated) versus "open" transition states in the aldol condensation, see: Heathcock, C. H. In Asymmetric Synthesis; Morrison, J. D., Ed.; Academic Press: Orlando, 1984; Vol. 3, p 154.
5. Kuwajima, I.; Nakamura, E. J. Am. Chem. Soc. 1975, 97, 3257.
6. Gingras, M. Tetrahedron Lett. 1991, 32, 7381.
7. Schwesinger, R.; Schlemper, H. Angew. Chem., Int. Ed. Engl. 1987, 26, 1167.
8. Dietl and Brannock reported 15-85% yields in C-alkylations of isobutyraldehyde and 2-ethylhexanal using a 50% aqueous NaOH-benzene two-phase system with tetrabutylammonium iodide as the transfer salt. See: Dietl, H. K.; Brannock, K. C. Tetrahedron Lett. 1973, 15, 1273.
9. 13C NMR, IR, and HREIMS.
10. 2 chromatography.
11. 1H NMR spectrum produced a 2.7% enhancement of the syn C7 proton, while no enhancement was observed for the C9 methyl protons. Irradiation of the C9 methyl protons resulted in a 0.9% enhancement for the C11 proton and a 0.6% enhancement of the ortho proton on the aryl group. For compound 16 irradiation of the C2 and C4 protons yielded a 4.5% enhancement in the aldehyde proton, but no enhancement was observed for the C9 methyl protons.
12. Evidence to support this was that alkylation of 2-methyl-2-butenal and 2-methyl-2-pentenal with benzyl bromide proceeded to give the expected C-alkylated products in 89% and 93% yields, respectively (isolated as their 2,4-dinitrophenylhydrazones).
13. Rawson, D. I.; Carpenter, B. K.; Hoffmann, H. M. R. J. Am. Chem. Soc. 1979, 101, 1786.
14. March, J. In Advanced Organic Chemistry, 4th ed.; John Wiley & Sons: New York, 1992; pp 250-252.