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  • Synthesis of polysubstituted iodobenzene derivatives from alkynylsilanes and 1,3-dienes via diels-alder/oxidation/iodination reaction sequence.

Synthesis of polysubstituted iodobenzene derivatives from alkynylsilanes and 1,3-dienes via diels-alder/oxidation/iodination reaction sequence.

Organic letters (2015-03-21)
Robert Möckel, Gerhard Hilt
ABSTRACT

The cobalt-catalyzed Diels-Alder reaction of trimethylsilyl-substituted alkynes with 1,3-dienes led to dihydroaromatic intermediates which were transformed into iodobenzene derivatives. For this transformation, the dihydroaromatic intermediates had to be oxidized and the trimethylsilyl-substituted arene had to undergo a silicon-iodine exchange reaction. For this purpose, a number of oxidizing agents and iodonium sources were tested in order to realize the desired two transformations in a single step. Eventually, the combination of tert-butyl hydroperoxide (TBHP), zinc iodide, and potassium carbonate led to the desired oxidation/iodination in good to excellent yields in a short reaction time at ambient temperatures.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Potassium carbonate, anhydrous, free-flowing, Redi-Dri, ReagentPlus®, 99%
Sigma-Aldrich
Potassium carbonate, puriss. p.a., ACS reagent, anhydrous, ≥99.0% (T)
Sigma-Aldrich
Potassium carbonate, anhydrous, free-flowing, −325 mesh, Redi-Dri, reagent grade, ≥98%
Sigma-Aldrich
Potassium carbonate, puriss., meets analytical specification of Ph. Helv., anhydrous, granulated, 99-101% (calc. to the dried substance)
Sigma-Aldrich
Potassium carbonate, ACS reagent, ≥99.0%
Sigma-Aldrich
Potassium carbonate, ReagentPlus®, 99%
Sigma-Aldrich
Potassium carbonate, reagent grade, ≥98%, powder, −325 mesh