Arylcarbonyl compounds

Arylcarbonyl Compounds from Allylic Alcohols and Phenylpalladium Acetate 2... 

HI. Formation of 3-Arylcarbonyl Compounds from Ailylic Alcohols... 

Arylcarbonyl Compounds as Initiators for Unsaturated Polyester/ Styrene Copolymerization Systems. Gel Time Determination and Reaction Curves. Ten blanks (gel time of 20 grams Vestopal A without initiator) gave a mean deviation from the average of 3.3% and a maximum deviation of 7.2%. Five measurements with l-phenyl-2-propanone as initiator gave a mean deviation from the average of 3.3% and a maximum deviation of 7.7%. An experimental error of 10% was therefore assumed and proved correct by spot checks. The exceptions (not used in the discussions) are most probably caused by the insolubility of the initiators in the reaction medium. 

Special Coupling Partners Phenol Derivatives and Arylcarbonyl Compounds... 

Arylcarbonyl compounds, such as carboxylic acids, aldehydes, acid chlorides, amides, and esters, have been increasingly used as an aryl source in arene-assembling cross-coupHng reactions. They are usually inexpensive and readily available compared to general cross-coupling partners [155]. In addition, these coupling reactions produce CO or CO2 as a by product instead of toxic metal halides. 

Enantioenriched a-arylcarboxylic acids with a tertiary a stereocenter are an important class of chiral building blocks that serve as useful intermediates in the synthesis of bioactive compounds. For the synthesis of enantioriched a-arylcarbonyl compounds, Lundin and Fu developed a nickel-catalyzed method for the asymmetric Suzuki aryla-tion of racemic a-chloroamides." Efficient reactivity was observed with NiBr2- diglyme and ligand 88, that are both commercially available. Thus, treatment of racemic... 

Under special conditions (addition of lithium amide, phase-transfer catalysis), compounds with apparently unactivated methylene groups (e.g., 5-methoxy-l-tetra-lone, Lombardo and Mander, 1980) or even with a methyl group at an arylcarbonyl group (Sugihara et al., 1987) undergo diazo transfer with arenesulfonyl azides. This is also the case for esters of 4-arylbut-3-enoic acid and related compounds (Davies et al., 1989, and references therein). 

We claim, however, that this reaction is likely to be more complex. The isolated intermediate salt may be the prototropic isomer 4.23 formed intermolecularly from 4.21, which is the primary steady-state intermediate. Compound 4.23 is energetically more favorable because in 4.23 — in contrast to 4.21 — conjugation (Ti-orbital overlap) between the arylcarbonyl part and the 4-toluenesulfonyl azide part is not interrupted by an sp C-atom. Intermediate 4.21 may, however, also react directly to give the diazoketone 4.22 via a cyclic transition state 4.24 that contains, however, a less favorable (Z)-azo group. The prototropy 4.21 4.23 was included at an early date for the mechanism of the diazo transfer from 4-toluenesulfonyl azide to the cyclopentadienyl anion by Roberts (see review Roberts, 1990, p. 217) and by Huisgen (1990). A transition state similar to 4.24 was mentioned by Balli et al. (1974) for the diazo transfer of azidinium salts to pyrazolin-5-one and 5-aminopyrazole compounds (see below). 

---