1931-49-3Relevant academic research and scientific papers
Vinylation of aromatic halides using inexpensive organosilicon reagents. Illustration of design of experiment protocols
Denmark, Scott E.,Butler, Christopher R.
, p. 3690 - 3704 (2008/10/09)
The preparation of styrenes by palladium-catalyzed cross-coupling of aromatic iodides and bromides with divinyltetramethyldisiloxane (DVDS) in the presence of inexpensive silanolate activators has been developed. To facilitate the discovery of optimal reaction conditions, Design of Experiment (DoE) protocols were used. By the guided selection of reagents, stoichiometries, temperatures, and solvents, the vinylation reaction was rapidly optimized with three stages consisting of ca. 175 experiments (of a possible 1440 combinations). A variety of aromatic iodides undergo cross-coupling at room temperature in the presence of potassium trimethylsilanoate using Pd(dba) 2 in DMF in good yields. Triphenylphosphine oxide is needed to extend catalyst lifetime. Application of these conditions to aryl bromides was accomplished by the development of two complementary protocols. First, the direct implementation of the successful reaction conditions using aryl iodides at elevated temperature in THF provided the corresponding styrenes in good to excellent yields. Alternatively, the use of potassium triethylsilanolate and a bulky "Buchwald-type" ligand allows for the vinylation reactions to occur at or just above room temperature. A wide range of bromides underwent coupling in good yields for each of the protocols described.
Tetraethylammonium bromide catalysed phase transfer reaction of potassium superoxide with hydrazones and tosylhydrazones
Kumar,Singh
, p. 579 - 583 (2007/10/03)
A variety of hydrazones and tosylhydrazones of carbonyl compounds have been investigated under the mild reaction conditions of potassium superoxide and tetraethylammonium bromide in dry dimethylformamide. As a result, hydrazones are generally transformed to their corresponding azines whereas tosylhydrazones undergo facile fragmentation to give the olefinic products in fairly good yields. The study highlights the use of tetraethylammonium bromide as an efficient and inexpensive catalyst for superoxide studies.
Electro-reductive cleavage of some tosylhydrazones in the presence of oxygen
Singh, Manorama,Singh, Krishna Nand,Misra, Ram Achal
, p. 173 - 176 (2007/10/02)
The superoxide ion induced fragmentation of tosylhydrazones of p-anisaldehyde (1a) 4-(dimethylamino)benzaldehyde (1b), 2-methylcyclohexanone (1c), 2,2-dimethylcyclohexanone (1d), spirodecan-6-one (1e) and 1-indanone (1f) at mercury catode in DMF affords the olefinic products (2a-f) in good yields.
