Moderate reactivity

Vinylboranes are interesting dienophiles in the Diels-Alder reaction. Alkenylboronic esters show moderate reactivity and give mixtures of exo and endo adducts with cyclopentadiene and 1,3-cyclohexadiene (441). Dichloroalkenylboranes are more reactive and dialkylalkenylboranes react even at room temperature (442—444). Dialkylalkenylboranes are omniphilic dienophiles insensitive to diene substitution (444). In situ formation of vinyl-boranes by transmetaHation of bromodialkylboranes with vinyl tri alkyl tin compounds makes possible a one-pot reaction, avoiding isolation of the intermediate vinylboranes (443). Other cycloadditions of alkenyl- and alkynylboranes are known (445). 

H0(CH20) H easy handling, moderate reactivity, stable at high water content... 

Unlike common commercial dianhydrides such as PMDA and BTDA, bis(ether anhydride)s possess moderate reactivity toward nucleophiles because of the electron-donating property of the ether groups. Bis(ether anhydtide)s are hardly affected by atmospheric moisture. The stabiUty and generally better solubiUty of bis(ether anhydtide)s provide significant advantages in manufacturing operations. 

DiaUyl fumarate polymerizes much more rapidly than diaUyl maleate. Because of its moderate reactivity, DAM is favored as a cross-linking and branching agent with some vinyl-type monomers (1). Cyclization from homopolymerizations in different concentrations in benzene has been investigated (91). DiaUyl itaconate and several other polyfunctional aUyl—vinyl monomers are available. 

The equivalent charge weight of TNT is calculated on the basis of the entire cloud content. FMRC recommends that a material-dependent yield factor be applied. Three types of material are distinguished Class I (relatively nonreactive materials such as propane, butane, and ordinary flammable liquids) Class II (moderately reactive materials such as ethylene, diethyl ether, and acrolein) and Class III (highly reactive materials such as acetylene). These classes were developed based on the work of Lewis (1980). Energy-based TNT equivalencies assigned to these classes are as follows ... 

Arylethenes are inner-outer-ring dienes in which the vinyl group is linked to an aromatic system. These dienes are poorly or moderately reactive the presence of electron-donating substituents in the diene moiety markedly increases their reactivity. Their cycloadditions are usually accelerated in order to be carried out under mild conditions. 1-Vinylnaphthalene is more reactive than 2-vinyl-naphthalene and styrenes. 

It has been shown (ref. 21) that a solvent which is both protic and nucleophilic, assists the formation of the bromination intermediates of moderately reactive olefins as styrenes in two ways, (Scheme 7). Firstly, the solvent initiates bromide ion formation electrophilically and, secondly, favours... 

In 2009, Buchmeiser and co-workers reported the synthesis of a novel ruthenium complex 54 based on a seven-membered NHC ligand [68] (Fig. 3.22). To examine the catalytic activity of complex 54 in the RCM reaction, the authors subjected the complex to a series of typical RCM reactions by using substrates 1, 3, and 5. Pre-catalyst 54 showed only moderate reactivity with 1 and 3 and no reaction occurred with 5. 

A wide variety of aromatic compounds can be brominated. Highly reactive ones, such as anilines and phenols, may undergo bromination at all activated positions. More selective reagents such as pyridinium bromide perbromide or tetraalkylammonium tribromides can be used in such cases.18 Moderately reactive compounds such as anilides, haloaromatics, and hydrocarbons can be readily brominated and the usual directing effects control the regiochemistry. Use of Lewis acid catalysts permits bromination of rings with deactivating substituents, such as nitro and cyano. 

Iodination of moderately reactive aromatics can be effected by mixtures of iodine and silver or mercuric salts.31 Hypoiodites are presumably the active iodinating species. Bis-(pyridi nc)iodonium salts can iodinate benzene and activated derivatives in the presence of strong acids such as HBF4 or CF3S03H.32... 

Aromatic rings are moderately reactive toward addition of free radicals (see Part A, Section 12.2) and certain synthetically useful substitution reactions involve free radical substitution. One example is the synthesis of biaryls.175... 

Once a moderately reactive iron cluster activates the first hydrogen molecule, it rapidly reacts to adsorb more hydrogen, eventually reaching a saturation level. The saturation studies by... 

Here again the high reactivity is due to the gain of aromatic stabilization in the adduct. Polycyclic aromatics are moderately reactive as the diene component in Diels-Alder reactions. Anthracene forms adducts with a number of dienophiles. The addition occurs at the centre ring. The naphthalene ring system is much less reactive. 

Comparison of their rate of onset and recovery of a treated mucosa has been made [37]. Fatty acids have strong and fast reactivity and allow for a fast recovery of the barrier function. Bile salts and salicylates are moderate, fast-acting agents with fast barrier-function recovery. Strong surfactants and chelators have strong or moderate reactivity and a slow recovery of barrier function. Solvents like dimethylsulfoxide and ethanol have moderate reactivity and act primarily as agents to improve drug miscibility in an aqueous environment. The enhancers listed above are also effective in the small intestine [22]. Enhancers that are more colon specific include ethylaceto-acetate, which must be first metabolically transformed to enamine [38]. 

Moderately reactive good leaving group via protonation ... 

Uozumi and coworkers have briefly investigated methanolysis of cyclic anhydrides catalyzed by chiral imidazolones. Moderate reactivity and selectivity was observed ... 

---