Reaction with protic reagents

Complexes 36 undergo a proton exchange reaction with protic reagents for example, a series of monomeric amido complexes are easily prepared using this route [45] (Equation 2.11 in Scheme 2.5). 

All three hydroxo species [M(OEP)(Me)(OH)] (M = P, As, Sb]) are sufficiently acidic to react with the aluminum porphyrin complex Al(OEP)Me, which is known to eliminate methane on reaction with protic reagents. Three novel binuclear... 

Homoleptic silylamido-Ln compounds [Ln <(Si le j2 LI or the more readily displaceable [Ln N(SiHMe2)2 3(thf)n] have been widely used as substrates for reaction with protic reagents H L. Some examples have already been described in Sections 4.3.3 and 4.3.5 ... 

Reactions of Doubly Bonded Tin Compounds with Protic Reagents... 

Reactions with Protic, Ionic, Polar Reagents. 250... 

Reactions with Protic, ionic, Poiar Reagents. The reactions of radical anions with proton donors include the reduction of arenes, the well-known Birch reduction, as well as alkynes by alkali metals in liquid ammonia. Both reactions have synthetic utility and belong to the few radical ion reactions included in elementary textbooks. 

Neutral homoleptic transition amide molecules are for the most part soluble in commonly used aprotic solvents. They are, in effect, hydrocarbon-soluble soiuces of M"ions, and because of the polarity of the M—N bond they can readily be used for the synthesis of a wide variety of reagents. The most common reactions involve the insertion of unsamrated species into the M—N bond or M—N bond cleavage reactions with protic molecules. Their utility can be illustrated by the reactions of some divalent Co) ) amides, shown in Scheme 6.2. 

The following example is a good illustration of these two facts the spirophosphorane 70 (Scheme 9), with a TBP structure, is a racemate of the enantiomers x and x, which can both be in tautomeric equilibrium with 70a, a derivative of tricoordinated phosphorus. The pentacoordinated P is electrophilic and can therefore undergo a number of reactions with nucleophilic reagents, whereas the tricoordinated P atom of 70a is nucleophilic or even biphilic, and 70a itself, with its OH group, has a nucleophilic protic centre with all its specific chemical properties. 

We have shown without any doubt the formation of carbanions obtained when trivalent phosphorus compounds react with an acetylenic compound. Trapping of these carbanionic species with protic reagents, alcohol for instance,leads to an ylid A. An alternative pathway involves reaction on the phosphorus atom leading to a phosphorane JB. 

Aminotin species are readily hydrolyzed and react with protic reagents (Scheme 18). Snbstitntion reactions occur with reactive halides (equations 83 and 84), as do addition reactions with heterocumnlenes, e g. 0=C=C=C=0... 

Despite the presence of a formally divalent carbon atom, CO is not in fact a particularly reactive molecule and much of its chemistry depends on the use of either extreme conditions, energetic reagents or some form of catalysis. Perhaps the simplest examples of such catalysis are found in the reactions of carbon monoxide with protic reagents such as alcohols or secondary amines, affording esters or amides of formic acid. These reactions are catalyzed by alkoxide or amide anions, respectively, and, as shown in Scheme 1, the key step is nucleophilic attack on CO by the catalyst to give a strongly basic alkoxyacyl or aminoacyl anion which is immediately trapped by proton transfer from the alcohol or amine, so generating the catalytic species. 

The metallacyclic compounds react with protic reagents to yield the corresponding substituted 1,3-butadienes and the iodination reactions give the 1,4-diiodo 1,3-butadiene derivatives (Scheme 122). Reactions with different unsaturated organic molecules have also been investigated. They catalyze the cyclotrimerization of a range of alkynes. Terminal alkynes with small substituents produce the 1,2,4-trisubstituted benzene, preferentially, in an exothermic reaction. The more bulky substrates BuTl CH and Me3SiC=CH react more slowly and only the symmetrical 1,3,5-isomer is produced (Scheme 122).174... 

It has been found that the aminoborylene complexes 23a,b-25 display extremely low reactivity towards nucleophilic substitution at the boron center. Consequently, they show high stability against both air and moisture for long periods (vide supra). Treatment of 23b with an excess of HCl, however, provided the corresponding chloroborylene complex [(/x-BCl) ( 5-C5H4Me)Mn(CO)2 2] (34). The weakly 7r-stabilized complex 34 undergoes a number of substitution reactions at the boron center with protic reagents (Scheme 15) [46,60]. Reaction of 34 with pyridine in the presence of H[BF4] results in the formation of the aminoborylene complex 41 via formal 1,4-hydroboration of pyridine [61,62]. 

Recent advances in the Staudinger reaction of tertiary phosphines with azido compounds have been reviewed.The reaction of the alkynylphosphine (88) with phenylazide yields the unstable intermediate (89), which in the presence of protic substances undergoes nucleophilic addition to the triple bond. The reactivity of the nitrogen-silicon bond of the phosphinimine derived from triphenylphosphine and trimethylsilylazide has been exploited in reactions with chloroformyl reagents to generate new functionalised phosphinimines, e.g., (90). ... 

In contrast to the P-N bond in alkylamino phosphines, the P-N bond in (l-pyrrolyl)phosphines seems to be rather stable toward solvolysis with protic reagents. However, they are easily oxidized with oxygen to produce the corresponding phosphine oxides [48, 49]. P(pyrrolyl)3, which has been frequently investigated for hydroformylation reactions, can even be recrystallized from methanol without decomposition [49]. The high stability toward protic reagents... 

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