Search results
Results From The WOW.Com Content Network
In organic chemistry, regioselectivity is the preference of chemical bonding or breaking in one direction over all other possible directions. [1] [2] It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base will abstract from an organic molecule, or where on a substituted benzene ring a further substituent will be added.
Hartwig and co-workers have succeeded in developing highly selective iridium catalysts with (R,R,R)-phosphoramidite L [11] The allylic aminations of a wide variety of achiral allylic esters proceeded with total conversion and superb regioselectivity in many cases. The reaction shown clearly illustrates the power of this methodology, wherein ...
High regioselectivity is obtained with unsymmetrical alkenes with a preference for a 1,2-relation of the ether group with the electron-deficient alkene-carbon. All this is exemplified in this aza Diels-Alder reaction : [ 9 ] [ 10 ]
For such 1,2-disubstituted olefins, regioselectivity can be observed only when one of the two substituents is a phenyl ring. In such cases, such as trans-1-phenylpropene, the boron atom is placed on the carbon adjacent to the phenyl ring. The observations above indicate that the addition of H-B bond to olefins is under electronic control rather ...
Chemoselectivity is the preferential reaction of a chemical reagent with one of two or more different functional groups. [1]In a chemoselective system, a reagent in the presence of an aldehyde and an ester would mostly target the aldehyde, even if it has the option to react with the ester.
3. Whole Foods Market. Popularity: 61% Fame: 95%. Whole Foods made organic and free-range mainstream, so it’s no surprise it ranks as the third most popular grocery chain in the country.For ...
Others described Trump as "dangerous" and "worrying" and questioned whether he really had Greenland's best interests at heart. "We are so few inhabitants," Jens Danielsen said.
Triethyl phosphonoacetate is a reagent for organic synthesis used in the Horner-Wadsworth-Emmons reaction (HWE) or the Horner-Emmons modification.. Triethyl phosphonoacetate can be added dropwise to sodium methoxide solution to prepare a phosphonate anion.