Traditional methods for forming carbon-carbon bonds between unsaturated moieties have a number of well-known difficulties. These cross-coupling reactions often...
Traditional methods for forming carbon-carbon bonds between unsaturated moieties have a number of well-known difficulties. These cross-coupling reactions often require harsh conditions, use difficult-to-handle precursors, and result in poisonous byproducts. This invention uses known materials-organosilacyclobutanes or simple organosilanols-in a new way to avoid these problems. The process involves subjecting these materials to stereospecific cross-coupling reactions with organic electrophiles in the presence of an activator (either a fluoride source or oxygen-based nucleophile) and a palladium catalyst. Under these mild conditions, carbon-carbon bonds are formed without the toxic byproducts associated with traditional cross-coupling methods.
This invention provides a mild, general and stereospecific method for the formation of carbon-carbon bonds between unsaturated moieties without the concomitant production of toxic byproducts. This new method addresses many of the difficulties associated with traditional cross-coupling techniques. By using organosilacyclobutanes or organosilanols, this process eliminates the need for processing in harsh conditions and using difficult-to-handle precursors. Most importantly, it eliminates the toxic byproducts that result from traditional methods. The cross-coupling begins with an organosilacyclobutane or organosilanol that is treated with a fluoride solution. After the initial exotherm subsides, the organic electrophile is added along with the palladium catalyst. The reactions times vary from 10 minutes to 7 hours at room temperature. The products then are isolated by removal of solvent and filtration through silica gel to remove salts and catalyst, followed by distillation. Occasionally filtration through a reverse phase (C-18) chromatography column is necessary to remove the byproduct. The products are formed in 65% to 93% of analytically pure material.
Organosilacyclobutanes or organosilanols are a preferable material for cross-coupling reactions:
The benefits of this invention accrue from its use of organosilacyclobutanes or organosilanols as the nucleophilic component in cross-coupling reactions. Unlike the materials used in traditional processes, these silicon-based moieties are chemically inert, have low molecular weight, are easy to introduce in a variety of organic structures, are stable to standard purification procedures, and can be activated by fluoride ions at room temperature. These features make the coupling process less complicated and less dangerous than traditional coupling methods.
Researchers from the University of Illinois have created a process for the epigenomic analysis of single cells. This process combines the uses of single cell...
Researchers from the University of Illinois have created a process for the epigenomic analysis of single cells. This process combines the uses of single cell microfluidics and chromatin immunoprecipitation (ChIP) for the analysis of DNA modifications in single cells.This technology has the potential to greatly decrease the number of cells needed from a biopsy to test for different cancers. It may also allow the study of traveling cell cancers that are only present in very small almost undetectable quantities.