Synthesis of Hydroxy-α-sanshool

Bo Wu; Kun Li; Patrick H. Toy

doi:10.1055/s-0032-1317172

Synlett, Inhaltsverzeichnis

Synlett 2012; 23(17): 2564-2566
DOI: 10.1055/s-0032-1317172

letter

Synthesis of Hydroxy-α-sanshool

Authors

Bo Wu

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. of China Fax: +852(2)8571586 eMail: phtoy@hku.hk
Kun Li

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. of China Fax: +852(2)8571586 eMail: phtoy@hku.hk
Patrick H. Toy*

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. of China Fax: +852(2)8571586 eMail: phtoy@hku.hk

Abstract

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Abstract

The amide hydroxy-α-sanshool is responsible for the mild numbing sensation experienced when Sichuan (or Szechuan) peppercorns (huajiao) are eaten. It has been synthesized in six steps from simple commercially available starting materials using Wittig reactions as the key transformations for construction of the carbon skeleton. The penultimate synthetic intermediate was 2E,6Z,8E,10E-dodecatetraenoic acid, and its crystalline nature allowed it, and thus hydroxy-α-sanshool, to be purified to a very high level of stereochemical homogeneity.

Key words

natural products - isomers - alkenes - Wittig reaction - aldehydes

Volltext

Referenzen

References and Notes

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10 See the Supporting Information for details.
11 This stereoselectivity is typical of such Wittig reactions involving unstabilized ylides, and we are currently exploring the purification of the E-isomer so that it can be used in the synthesis of β-sanshool derivatives.
12 Characterization data for synthetic 1: ¹H NMR (400 MHz, CDCl₃): δ = 1.21 (s, 6 H), 1.75–1.77 (d, J = 7.2 Hz, 3 H), 2.23–2.35 (m, 4 H), 3.13 (s, 1 H), 3.29–3.31 (d, J = 6.0 Hz, 2 H), 5.31–5.37 (dt, J = 10.4, 7.4 Hz, 1 H), 5.67–5.75 (dq, J = 14.0, 7.2 Hz, 1 H), 5.83–5.87 (d, J = 15.2 Hz, 1 H), 5.97–6.03 (dd, J = 10.8, 10.8 Hz, 1 H), 6.19–6.06 (m, 2 H), 6.27–6.33 (m, 2 H), 6.80–6.87 (dt, J = 13.2, 6.4 Hz, 1 H); ¹³C NMR (100 MHz, CDCl₃): δ = 18.4, 26.5, 27.2, 32.1, 50.6, 70.8, 124.0, 125.2, 129.4, 129.7, 130.2, 131.8, 133.6, 144.1, 167.2. This matches the data previously reported for material isolated from natural sources.^1a

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Zusatzmaterial

Supporting Information (PDF)