Cycloaddition Products from (1-Diazo-2-oxoalkyl)silanes and Cyclopropenes. A Silatropic 2,3-Diazabicyclo[3.1.0]hex-3-ene/1,4-Dihydropyridazine Equilibrium
✍ Scribed by Munschauer, Rainer ;Maas, Gerhard
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1992
- Tongue
- English
- Weight
- 868 KB
- Volume
- 125
- Category
- Article
- ISSN
- 0009-2940
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✦ Synopsis
Abstract
(1‐Diazo‐2‐oxoalkyl)silanes 1a–h react with cyclopropene 4 to form 2‐silyl‐2,3‐diazabicyclo[3.1.0]hex‐3‐enes 5 and/or 1‐silyll‐1,4‐dihydropyridazines 6. In most cases, a temperature‐ and solvent‐dependent equilibrium 5 ⇄ 6 maintained by an N →N′ silyl shift exists in solution. With cyclopropene 10, only the 1‐silyl‐1,4‐dihydropyridazines 11 are obtained. None of the 1:1 adducts corresponds to the product expected from a [3 + 2] cycloaddition reaction between the components. Evidence is presented that 1‐diazo‐2‐siloxy‐1‐alkenes 2 are initially formed from 1 by a 1,3‐(C → O) silyl shift and are then trapped by the cyclopropene in a 1,3‐dipolar cycloaddition reaction.