Dolbier HW Solutions 599

Dolbier HW Solutions 599 - o-allyl phenol. The synthesis is...

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Other synthetic routes are of course possible. One of the earliest approaches used a Grignard reaction to attach the side chain. The resulting secondary alcohol can then be dehydrated to the same alkene intermediate prepared in the preceding synthetic scheme. Again, hydrogenation of the double bond and ether cleavage leads to the desired 3-pentadecylcatechol. 24.23 Recall that the Claisen rearrangement converts an aryl allyl ether to an ortho-substituted allyl phe- nol. The presence of an allyl substituent in the product ortho to an aryl ether thus suggests the fol- lowing retrosynthesis: As reported in the literature synthesis, the starting phenol may be converted to the corresponding allyl ether by reaction with allyl bromide in the presence of base. This step was accomplished in 80% yield. Heating the allyl ether yields the
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Unformatted text preview: o-allyl phenol. The synthesis is completed by methylation of the phenolic oxygen and saponi f cation of the acetate ester. The f nal three steps of the synthesis proceeded in an 82% overall yield. OH CH 3 O H 3 C CH 2 CH CH 2 OCCH 3 O OCH 3 CH 3 O H 3 C CH 2 CH CH 2 OCCH 3 O OCH 3 CH 3 O H 3 C CH 2 CH CH 2 OH K 2 CO 3 CH 3 I 1. KOH, CH 3 OH 2. H 1 OH CH 3 O H 3 C OCCH 3 O OCH 2 CH OCCH 3 O CH 3 O H 3 C CH 2 OH OCCH 3 O CH 3 O H 3 C CH 2 CH CH 2 200 8 C 3 h K 2 CO 3 H 2 C CHCH 2 Br OCH 3 OH CH 3 O H 3 C CH 2 CH CH 2 OCH 2 CH OCCH 3 O CH 3 O H 3 C CH 2 CH 3 O CHCH 2 (CH 2 ) 12 CH 3 OH OCH 3 CH 3 O CH CH(CH 2 ) 12 CH 3 OCH 3 H 1 CH 3 O CH O OCH 3 2,3-Dimethoxy-benzaldehyde CH 3 O CHCH 2 (CH 2 ) 12 CH 3 OH OCH 3 1 CH 3 (CH 2 ) 12 CH 2 MgBr 1. diethyl ether 2. H 3 O 1 PHENOLS 693...
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This note was uploaded on 10/03/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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