Selective 1,4-Hydroboration of Phenyl 1-Alkenyl Ketones with 9-Borabicyclo [33.1]nonane and Catecholborane Forming Boron (Z)-Enolates

Synlett

Volumn 1991, Issue 5, 1991, Pages 349-350

  Matsumoto, Yonetatsu ^a   Hayashi, Tamio ^a  

^a HOKKAIDO UNIVERSITY   (Japan)

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Indexed keywords

EID: 85064416866     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-1991-34744     Document Type: Article

References (11)

1. Evans, D. A.; Fu, G. C. /. Org. Chem. 1990,55, 5678.
2. Boldrini, G. P.; Mancini, F.; Tagliavini, E.; Trombini, C; Umani-Ronchi, A. J. Chem. Soc., Chem. Commun. 1990,1680.
3. Boldrini, G. P.; Bortolotti, M.; Tagliavini, E.; Trombini, C; Umani-Ronchi, A. Tetrahedron Lett. 1991,32,1229.
4. Evans, D. A. Top. Stereochem. 1982,13,1. Paterson, I. Chem. lnd. 1988, 390.
5. Brown, H. C; Dhar, R. K.; Bakshi, R. K.; Pandiarajan, P. K.; Singaram, B. J. Am. Chem. Soc. 1989, 111, 3441.
6. >H NMR (CDCI3/TMS) for (Z)-4b: 8 0.10 (s, 9 H), 1.01 (t, J = 7.4 Hz, 3 H), 2.19 (quint, / = 7.4 Hz, 2 H), 5.21 (t, / = 7.1 Hz, 1 H), 7.1-7.6 (m, 5 H). The vinylic proton of the £ isomer, (E)-4b, which was obtained as a minor isomer by thermal isomerization of the magnesium enolate generated from (Z)-2b, appeared at 5.46 (t, J = 7.1 Hz). It has been reported that the vinylic proton of Z isomer appears at a higher field than that of E isomer Davis, F. A.
7. Lai, G. S.; Wei, J. Tetrahedron Lett. 1988,29,4269
8. See also, House, H. O.; Czuba, L. J.; Gall, M.; Olmstead, H. D. J. Org. Chem. 1969,34, 2324.
9. Silyl enol ether 4a, derived from 2a, was confirmed to be a Z isomer by the lU and 13C NMR: Heathcock, C. H.; Buse, C. T.; Kleschick, W. A.; Pirrung, M. C; Sohn, J. E.; Lampe, J. J. Org. Chem. 1980,45, 3441.
10. Chikashita, H.; Tame, S.; Yamada, S.; Itoh, K. Bull. Chem. Soc. Jpn. 1990,63, 497.
11. For 6a, see Mukai, C; Hashizume, S.; Nagami, K.; Hanaoka, M Chem. Pharm. Bull. 1990,38,1509. Heathcock, C. H.; Davidsen, S. K.; Hug, K. T.; Flippen, L. A. J. Org. Chem. 1986,51,3027. >H NMR (CDCI3/TMS) for jy/i-6a: 6 1.89 (d, J 7.3 Hz, 3 H), 3.66 (d, / = 2.2 Hz, 1H, Off), 3.70 (qd, J = 7.3 and 3.2 Hz, 1 H), 5.23 (dd, J 3.2 and 2.2 Hz, 1 H), 7.2-7.7,7.8-8.0 (m, 10 H). jyn-6b: 5 0.77 (t, / = 15 Hz, 3 H), 1.6-2.2 (m, 2 H), 3.25 (bs, 1 H, Off), 3.74 (dt, J = 8.4 and 4.8 Hz, 1 H), 5.07 (d, / = 4.8 Hz, 1 H), 7.1-7.6, 7.8-8.0 (m, 10 H). nft-6b: 5 0.79 (t, / = 7.4 Hz, 3 H), 1.4-1.9 (m, 2 H), 3.16 (d, / = 5.3 Hz, 1 H, Off), 3.77 (td, J 7.4 and 5.5 Hz, 1 H), 5.01 (dd, / = 7.3 and 5.3 Hz, 1 H), 7.2-7.6, 7.8-8.0 (m, 10 H). syn-6c: 5 3.0-3.3 (m, 2 H), 3.31 (bs, 1 H, Off), 4.03 (dt, / = 9.0 and 4.6 Hz, 1 H), 5.09 (d, / = 4.6 Hz, 1 H), 6.8-7.8 (m, 15 H). 6e: 6 1.18 (s, 3 H), 1.24 (s, 3 H), 3.00 (d, J = 2.9 Hz, 1H, Off), 5.14 (d, J = 2.9 Hz, 1 H),7.2-7.7 (m, 10 H).