61263-73-8Relevant articles and documents
Studies in Terpenoids : Part LII - Elaboration of 6-Methoxy-1,4-dimethyltetralin and 7-Methoxy-1,4-dimethyltetralol to Emmotin-G via Their Vilsmeier Reaction Products
Velusamy, T. P.,Rao, G. S. Krishna
, p. 351 - 354 (2007/10/02)
6-Methoxy-1,4-dimethyltetralin (I), a key intermediate in the synthesis of emmotin-G (II) has been obtained by two new routes.Reaction of p-anisylmagnesium bromide with allylacetone (III) gives a mixture of 5-p-anisylhex-1-en-5-ol (V) and 5-p-anisylhexa-1,4-diene (VI).Birch reduction of the hexenol-hexadiene mixture affords the arylhexene (VII) which on treatment with polyphosphoric acid cyclizes to the tetralin (I).Hydrogenolysis of 7-methoxy-1,4-dimethyl-1-tetralol (IX), the Grignard reaction product of 7-methoxy-4-methyl-1-tetralone VIII), with methylmagnesium iodide gives I, thus constituting a second and shorter synthesis of I.Vilsmeier reaction of the tetralol (IX) gives a mixture of formyldihydronaphthalenes (X) and (XI), the former giving the known naphthaldehyde (XII) on dehydrogenation.Much better yield of XII has been secured from the semicarbazone of the Vilsmeier reaction product (XIII) of the tetralin (I) bei dehydrogenation and hydrolysis.Oxidation and demethylation of XII gives 3-hydroxy-5,8-dimethyl-2-naphthoic acid (XVIa).Grignard reaction on its methyl ester (XVIb) with CH3MgI affords emmotin-G (II), identical with the natural product.
