Facile Aromatic Claisen Rearrangement Catalysed by Tin(IV) Chloride

Abstract

Allyl aryl ethers undergo facile Claisen rearrangement under mild conditions catalysed by tin(IV) chloride.

Key words

Claisen rearrangement - allyl aryl ethers - Lewis acid - tin(IV) chloride

References and Notes

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20

7-Methoxy-2,5-dimethyl-dihydrobenzofuran (Entry 10)Obtained as a colourless solid. Crystallised from Et₂O-PE, mp43-44 °C. ¹H NMR (300 MHz, CDCl₃): δ = 1.51 (d, J = 11.5 Hz, 3 H), 2.28 (s, 3 H), 3.02 (dd, A of ABX, J _AB = 13.8 Hz, 1 H), 3.04 (dd, B of ABX, J _BA = 13.8 Hz, 1 H)_, 3.87 (s, 3 H), 4.40 (sext, X of ABX, J _AX = J _BX = 6.6 Hz,1 H), 6.58 (s, 1 H), 6.60 (s, 1 H). ¹³C NMR (75 MHz, CDCl₃): δ = 21.2, 24.9, 41.2, 56.0, 57.7, 110.3, 123.6, 123.8, 128.8, 141.6, 146.2. HRMS (ES+ve): m/z calcd for C₁₁H₁₄O₂ [M + Na]⁺: 201.0892; found: 201.0889.