GC_MS (Hive Bee)
02-09-03 18:13
No 405976
      Benzo-1,3-dioxoles and LTA  Bookmark   

This post is more a reaction/addition to Post 405635 (demorol: "Cheap aromatic iodination & bromination", Novel Discourse) In that thread, I mentioned I read something about the formation of quinones when e.g. benzene-1,3-dioxole would be reacted with LTA (lead tetraacetate). I found some of my old notes on the subject, since I had a dream once reacting LTA with benzene-1,3-dioxole to obtain new precursors. Allow me...

Taken from: Comprehensive Heterocyclic Chemistry, Vol 6: Five membered rings with two or more O, S or N atoms Chapter: Dioxoles and oxathioles

p 766: fused benzene rings

In electrophilic substitution reactions of benzo-1,3-dioxoles, only para-derivatives with respect to the oxygen atoms are formed. This differs from benzo-1,4-benzodioxanes where some ortho-isomer is obtained as well, and probably reflects the coplanarity of the rings in benzodioxoles resulting in an increased mesomeric effect <81H(15)1395>. Benzo-1,3-oxathiole derivatives undergo electrophilic substitution at the 5-position, i.e. para to the oxygen atom <53JCS1514>, although attack at the sulfer atom may be a complicating factor. 2,2-disubstituted benzo-1,3-dioxoles are oxidized by lead tetraacetate (LTA) to 5-acetoxy and 5,6-dione derivatives, as shown in equation (11) <80AJC527>. If the 2-position is not blocked, oxidation occurs there preferentially. The quinones are probably formed via a tetraacetoxy intermediate in a manner analogous to the oxidation of naphtyl ethers <79AJC1749>. As expected, metallation with n-BuLi takes place ortho to the oxygen atom in both systems provided that the 2-position is blocked.

Equation 11:
     C                              C                          C
   /   \                          /   \                      /   \
  C     C---O       LTA    AcO---C     C---O             O==C     C---O
  |     |     \   ------>        |     |     \    +         |     |     \
  |     |     /                  |     |     /              |     |     /
  C     C---O                    C     C---O             O==C     C---O
   \   /                          \   /                      \   /
     C                              C                          C

80AJC527: ER Cole, G Crank, HTH Minh. Aust J Chem 33 (1980) 527-

My idea was to exploit the reaction to obtain as much as possible of one of the two compounds presented. The 5-acetoxybenzodioxole could be used for 3,4-methylenedioxy-5-alkoxyamphetamines, while the 5,6-dione might be useful for 2,3-methylenedioxy-5,6-dialkoxyamphetamines or 2,3,5,6-dimethylenedioxyamphetamines:

          /   \
     O---C     C---O
   /     |     |     \
   \     |     |     /
     O---C     C---O
          \   /

If there are any bees out there interested in this, and they'd happen to have access to the mentioned Aust J Chem article, it would be most kind of them to post the details in this thread. Any remarks welcome, off course.

EDIT: Post 185131 (hest: "New Amph.  more potent than LSD", Serious Chemistry) is an example why latter compound might be interesting...

Abusus non tollit usum