
%0 Journal Article
%A Collins, DJ 
%A Rutschmann, SB 
%T Enolic Ortho Esters. II. Tandem Nucleophilic Electrophilic Dimethylation of 4',4'-Dimethyl-3,4,5,8-tetrahydrospiro[2H-1-Benzopyran-2,2'-[1,3]dioxolan]
%J Australian Journal of Chemistry
%D 1989/09/01
%V 42
%N 9
%P 1447-1454
%K 
%R https://doi.org/10.1071/CH9891447
%U https://www.publish.csiro.au/paper/CH9891447 
%X Reaction of 4&#8242;,4&#8242;-dimethyl-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2&#8242;-[l,3]dioxolan](9) with methylmagnesium iodide in benzene or toluene at 40º gave the iodomagnesium enolate acetal (10) which upon in situ reaction with methyl iodide afforded 56% of pure 6 &#958;-methyl- 6-[2&#8242;-(2&#8243;,4&#8243;,4&#8243;-trimethyl-1&#8243;,3&#8243;-dioxolan 2&#8243;yl)ethyl]cyclohex-3-en-one (11), the product of tandem nucleophilic/electrophilic dimethylation . Aqueous ammonium chloride workup of the iodomagnesium  enolate (10) gave 6-[2&#8242;-(2&#8243;,4&#8243;,4&#8243;-trimethyl-1&#8243;,3&#8243;-dioxolan 2&#8243;yl)ethyl] cyclohex-3-en-1-one (7). Some further transformations of the methylated keto acetal (11) are described. 
