Download PDF
Synlett 2006(4): 0595-0599  
DOI: 10.1055/s-2006-933099
LETTER
© Georg Thieme Verlag Stuttgart · New York

Diastereoselective Baylis-Hillman Reaction: First Use of Sugar-Derived α,β-Unsaturated δ-Lactone as Chiral Michael Acceptor [1]

Palakodety Radha Krishna*a, P. Srinivas Reddya, M. Narsingama, B. Sateeshb, G. Narahari Sastry*b
a D-206/B, Discovery Laboratory, Organic Chemistry Division-III, Indian Institute of Chemical Technology, Hyderabad 500007, India
Fax: +91(40)27160387; e-Mail: prkgenius@iict.res.in;
b Molecular Modeling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology, Hyderabad 500007, India
e-Mail: gnsastry@yahoo.com;
Further Information

Publication History

Received 21 November 2005
Publication Date:
20 February 2006 (online)

    Permissions and Reprints All articles of this category

Abstract

Diastereoselective Baylis-Hillman reaction of sugar-derived α,β-unsaturated δ-lactone with several aromatic aldehydes in presence of DABCO (50 mol%) to afford adducts in moderate to good yields (49-75%) with 30-82% de is being reported for the first time. Quantum chemical calculations based on the stabilities of transition structures and on the stabilities of zwitterionic intermediates rationalized the experimental observations.

Key words

sugar-derived α,β-unsaturated δ-lactones - diastereo­selective Baylis-Hillman reactions - 2-C-branched glycosides - ­zwitterion intermediates - computational studies - transition state structures

1

IICT communication no. 050728.

1

IICT communication no. 050728.

14

General Experimental Procedure. To a stirred solution of lactone (1.5 mmol) in anhyd DMSO (1.5 mL), aldehyde (1 mmol) was added followed by DABCO (0.5 mmol) and the reaction mixture stirred for 36 h at r.t. After completion of the reaction (TLC), the reaction mixture was diluted with EtOAc (20 mL), washed sequentially with H2O (1 × 15 mL), brine (2 × 10 mL), concentrated and dried (Na2SO4). The residue was purified by chromatography on silica gel (120 mesh, n-hexane-EtOAc, 6:4) to give the corresponding adduct. Spectral Data for Selected Compounds.
Compound 3a: light-yellow syrup; [α]D +20.1 (c 1.1, CHCl3). 1H NMR (200 MHz, CDCl3 TMS): δ = 8.16 (d, 2 H, J = 9.06 Hz, Ar-H), 7.64 (d, 2 H, J = 9.06 Hz, Ar-H), 6.94 (d, 0.91 H, J = 5.50 Hz, olefinic), 6.88 (d, 0.09 H, J = 1.51 Hz, olefinic), 5.62 (s, 1 H, benzylic), 5.52 (dd, 1 H, J = 3.00, 6.79 Hz, H-4), 4.61 (m, 1 H, H-5), 4.27-4.1 (m, 2 H, H-6), 2.13 (s, 3 H, CH3), 2.01 (s, 3 H, CH3). 13C NMR (75 MHz, CDCl3, TMS): δ = 170.1, 170.0, 160.2, 148.2, 147.8, 139.0, 134.0, 128.0, 124.0, 76.0, 71.0, 61.5, 61.0, 23.0, 21.0. FAB-MS: m/z = 379 [M]+, 362 [M - OH]+. IR (neat): 3399, 2925, 1716, 1349, 1026, 823 cm-1. Anal. Calcd for C17H17NO9: C, 53.83; H, 4.52. Found: C, 53.77; H, 4. 47.
Compound 3b: pale-yellow syrup; [α]D -78.3 (c 0.27, CHCl3). 1H NMR (300 MHz, CDCl3, TMS): δ = 7.35 (m, 3 H, Ar-H), 6.67 (d, 0.85 H, J = 6.04 Hz, olefinic), 6.58 (d, 0.15 H, J = 2.26 Hz, olefinic), 5.55 (m, 1 H, benzylic), 5.34 (dd, J = 3.02, 6.04 Hz, H-4), 4.72 (m, 0.85 H, H-5), 4.58 (m, 0.15 H, H-5), 4.40-4.10 (m, 2 H, H-6), 2.15 (s, 3 H, CH3), 2.05 (s, 3 H, CH3). ES-MS: m/z = 317 [M+ -2 × CH3CO]. IR (neat): 3469, 3031, 2925, 1740, 1455, 1372, 1225, 1047, 832, 761 cm-1. Anal. Calcd for C17H16Cl2O7: C, 50.64; H, 4.00. Found: C, 50.58; H, 3.79.
Compound 3c: light-yellow syrup; [α]D +39.2 (c 0.7, CHCl3). 1H NMR (200 MHz, CDCl3, TMS): δ = 8.00 (d, 1 H, J = 7.92 Hz, Ar-H), 7.84 (d, 1 H, J = 7.13 Hz, Ar-H), 7.65 (t, 1 H, J = 7.92 Hz, Ar-H), 7.50 (t, 1 H, J = 8.71 Hz, Ar-H), 6.54 (d, 0.88 H, J = 6.33 Hz, olefinic), 6.30 (d, 0.12 H, J = 1.58 Hz, olefinic), 6.17 (s, 1 H, benzylic), 5.53 (dd, 0.88 H, J = 1.58, 7.92 Hz, H-4), 5.26 (dd, 0.12 H, J = 2.37, 6.33 Hz, H-4), 4.67 (dt, 0.12 H, J = 2.37, 7.13, 12.60 Hz, H-5), 4.55 (dt, 0.88 H, J = 3.17, 7.92, 12.67 Hz, H-5), 4.40-4.20 (m, 2 H, H-6), 2.09 (s, 3 H, CH3), 2.06 (s, 3 H, CH3). 13C NMR (75 MHz, CDCl3, TMS): δ = 170.3, 169.5, 160.3, 138.2, 137.8, 134.7, 134.4, 134.0, 133.9, 129.13, 124.94, 75.9, 67.0, 63.8, 61.7, 20.6, 20.4. FAB-MS: m/z = 379 [M]+, 362 [M - OH]+, 293 [M - 2 × COCH3]+. IR (neat): 3463, 2929, 2885, 1739, 1528, 1368, 1220, 1051, 755 cm-1. Anal. Calcd for C17H17NO9: C, 53.83; H, 4.52. Found: C, 53.76; H, 4.47. Compound 3d: pale yellow syrup; [α]D +133.0 (c 0.1, CHCl3). 1H NMR (200 MHz, CDCl3, TMS): δ = 7.35 (m, 2 H, Ar-H), 7.05 (m, 2 H, Ar-H), 6.65 (d, 0.7 H, J = 5.94 Hz, olefinic), 6.58 (d, 0.3 H, J = 2.23 Hz, olefinic), 5.52 (br s, 1 H, benzylic), 5.30 (dd, 1 H, J = 2.97, 5.94 Hz, H-4), 4.70 (m, 0.7 H, H-5), 4.58 (m, 0.3 H, H-5), 4.40-4.10 (m, 2 H, H-6), 3.30 (br s, 0.7 H, OH), 2.95 (br s, 0.3 H, OH), 2.15 (s, 0.9 H, CH3), 2.12 (s, 2.1 H, CH3), 2.09 (s, 2.1 H, CH3), 2.03 (s, 0.9 H, CH3). ES-MS: m/z = 335 [M+ - OH]. Anal. Calcd for C17H17FO7: C, 57.96; H, 4.86. Found: C, 57.91; H, 4.77.