Carbon-hydrogen bonds solid-phase reactions

Scheme 29). Presumably, the two additional carbons come from 1 equiv of Meldrum s acid and the hydrogens derive from the solvent. A similar Meldrum s acid with two conjugated exocyclic double bonds was obtained from the reaction of Meldrum s acid with vinylogous Viehe salt in 93% yield <1997S573>. A polymer-bonded Meldrum s acid for solid-phase synthesis was also reported <2004CHJ212>. 

The radical products of low-temperature reactions of hydrogen atoms with a number of thiophen derivatives in the solid phase have been studied. In the case of 2-methylthiophen, thiophen-2-aldehyde, and 2-acetothienone, e.s.r. studies indicate that the hydrogen atoms are added to the ring at the C=C bonds, forming radicals with an unpaired electron on the carbon atom. In the interaction of 3-methylthiophen with hydrogen... 

The sulfonate ester 520 is able to release hydrogenated or deuterated compounds 528 by addition of HCO2H or DCO2D, triethylamine and Pd(OAC)2-dppp as the catalyst-ligand system. Carbon-carbon bond-forming reactions have also been combined with the simultaneous cleavage of the Hnker. Thus, the Mizoroki-Heck reaction as well as Suzuki-Miyaura reaction have been performed on solid phase and gave styrene 532 and biaryl systems 530, respectively (Scheme 80). 

The foundation for the present industry was laid in 1897 when Sabatier and Senderens illustrated the catalytic effect of nickel in vapor-phase hydrogenation reactions. The earliest technical application, bf- hydrogenation was in the reduction of the double bonds between two carbon atoms for the purpose of converting liquid fats into solid fats, or as it is often called, fat hardening. This industry is now very large. 

The most common type of reduction reaction over solid supports is hydrogenation [98, 99]. However, as this class of reaction involves hydrogen in the gas phase, it does not fall within the bounds of this chapter. In liquid phase processes the most widely investigated type of reaction is the reduction of compounds containing carbon-oxygen double bonds. Ketones and aldehydes are readily reduced by a number of methods using solid catalysts or supported reagents [100]. 

---