Intermolecular reaction compounds

Unlike the intermolecular reaction, the intramolecular aminopalladation proceeds more easily[13,14,166], Methylindole (164) is obtained by the intramolecular exo amination of 2-allylaniline (163). If there is another olefinic bond in the same molecule, the aminopalladation product 165 undergoes intramolecular alkene insertion to give the tricyclic compound 166[178]. 2,2-Dimethyl-l,2-dihydroquinoline (168) is obtained by endo cyclization of 2-(3,3-dimethyiallyl)aniline (167). The oxidative amination proceeds smoothly... 

Intramolecular reactions with alkenes. While the intermolecular reaction is limited to unhindered alkenes, the intramolecular version permits the participation of even hindered substituted alkenes, and various cyclic compounds are prepared by the intramolecular Heck reaction. Particularly the... 

With a radical-scavenging compound present in the reaction mixture, an alkyl radical species like 5 can be trapped, thus suggesting a fast conversion of the alkoxy radical 3 by intramolecular hydrogen abstraction, followed by a slow intermolecular reaction with nitrous oxide. 

Acyclic diene molecules are capable of undergoing intramolecular and intermolec-ular reactions in the presence of certain transition metal catalysts molybdenum alkylidene and ruthenium carbene complexes, for example [50, 51]. The intramolecular reaction, called ring-closing olefin metathesis (RCM), affords cyclic compounds, while the intermolecular reaction, called acyclic diene metathesis (ADMET) polymerization, provides oligomers and polymers. Alteration of the dilution of the reaction mixture can to some extent control the intrinsic competition between RCM and ADMET. 

These fragments either combine intramolecularly to form the ortho and para nitro compounds or dissociate completely and then undergo an intermolecular reaction to form the same products. The theory was not developed to include a detailed transition state and no mention was made of how the para isomer was formed. Reduction of the cation-radical could give the amine (which was observed experimentally76), but one would expect the concurrent formation of nitrogen dioxide and hence nitrite and nitrate ions however, the latter has never been... 

Compound 59a underwent intermolecular reactions characteristic of silenes (Scheme 19). Water added instantly across the Si=C double bond of the I -silaallene is expected to give vinylhydroxysilane 65 in 71% yield, and methanol was added... 

The high-dilution and template methods are frequently used in the synthesis of cyclic compounds with the aim of increasing the yield. The former method is carried out at substrate concentrations lower than 1 mM [18-20]. This reaction condition decreases the contact of the substrate molecules in the solution. The linear intermediate produced prefers the intramolecular cyclization reaction rather than the intermolecular reaction. Therefore, this reaction condition is useful for the intramolecular reaction, method B (Fig. 2). 

In the intermolecular reactions between anthocyaifins and flavonoids mediated by acetaldehyde, new compounds linked by an ethyl bridge are formed. Three new compounds were detected by the reaction of malvidin 3-glucoside and proanthocy-... 

This behaviour was rationalised by a stepwise reduction mechanism, in which a high catalyst or KOH concentration gives a high hydride concentration and leads to the aniline formation and suppression of intermolecular reactions to the dimeric azo-compound. 

The effectiveness of these intermolecular reactions depends on the relative reactivity of the two components, since self-metathesis leading to dimeric products will occur if one compound is more reactive than the other. 

The reactions of the six-membered chlorocyclophosphazene were studied with a number of aliphatic diamines (169 175), aromatic diamines (176), aliphatic diols (177-179), aromatic diols (180,181) and compounds containing amino and hydroxyl functional groups (169,170,182). This subject has been reviewed (11,16,20). There are at least five different reaction products that are possible (Fig. 19). Replacement of two chlorine atoms from the same phosphorus atom produces a spirocyclic product. Replacement of two chlorine atoms from two different phosphorus atoms in the same molecule produces an ansa product. Reaction of only one end of the difunctional reagent, resulting in the substitution of only one chlorine atom, leads to an open-chain compound. Intermolecular bridged compounds are formed when the difunc-... 

When guest molecules are arranged together in the channel of a host-guest inclusion complex, intermolecular reactions of the guest compound may proceed stereoselec-tively and efficiently. An enantioselective reaction is expected when optically active host compounds are used. 

Another possibility here is to use entropic acceleration. In this way, it is possible to use a substrate that first reacts in an intramolecular mode to give an intermediate, which then undergoes an intermolecular reaction with a second molecule. An impressive older example is a radical cyclization/trapping in the synthesis of prostaglandin F2a, as described by the Stork group [20]. A key step here is the radical transformation of the iodo compound 0-32 using uliu3Sril I formed in situ from... 

Efforts to realize an intramolecular version of the above reactions met with limited success when monocyclic 4-thio-substituted (3-lactams were used. Cu(acac)2-catalyzed decomposition of diazoketone 358 produced the epimeric carbapenams 359 a, b together with the oxapenam derivative 360 341 these compounds correspond to the C4/S insertion products obtained in intermolecular reactions. Oxapenams were obtained exclusively when the acrylate residue in 359 was replaced by an aryl or heteroaryl substituent 275 342). The different reaction mode of diazoketones 290a, b, which furnish mainly or exclusively carbonyl ylide rather than sulfur ylide derived products, has already been mentioned (Sect. 5.2). 

The photochemistry of ally 1-substituted Group 14 metal compounds can be divided into two sections, namely photoisomerization reactions, and those involving some kind of intermolecular reaction. 

Intermolecular Reactions Intermolecular 1,3-dipolar cycloaddition reactions of nitrones to olefins seem to be the most studied. They are widely used for the synthesis of different enantiomerically pure compounds, including biologically active ones. For example, two new glycosidase inhibitors have been obtained by the nitrone cycloaddition strategy (Fig. 2.32) (733). 

In Section 9.2, intermolecular reactions of titanium—acetylene complexes with acetylenes, allenes, alkenes, and allylic compounds were discussed. This section describes the intramolecular coupling of bis-unsaturated compounds, including dienes, enynes, and diynes, as formulated in Eq. 9.49. As the titanium alkoxide is very inexpensive, the reactions in Eq. 9.49 represent one of the most economical methods for accomplishing the formation of metallacycles of this type [1,2]. Moreover, the titanium alkoxide based method enables several new synthetic transformations that are not viable by conventional metallocene-mediated methods. 

Many of these reactions are not observed at all when the relevant groups are allowed to come together in bimolecular processes in aqueous solution. For mechanistic work involving intermolecular reactions, therefore, it is necessary to use activated substrates. Much of what we know about the relevant reactions of esters, for example, comes from studies using aryl esters like p-nitrophenyl acetate, or acyl-activated compounds like ethyl trifluoroacetate (Bruice and Benkovic, 1966 Jencks, 1969 Bender, 1971). 

In a few, but important, cases, EM s have been calculated not from rate constants but from product ratios. Where the effective molarity is low, competition between intramolecular and intermolecular reactions of the same compound may be observed, as in Freundlich s early work on the cyclization of w-bromoalkylamines (1) described by Salomon (1936). The inter-... 

The reference intermolecular reaction for all the compounds listed, except A.4.1, is the Sn2 reaction between potassium butanoate and n-butyl bromide measured under the same conditions 99 1 v/v dimethyl sulphoxide-water at 50° (Galli et al., 1973)... 

The reference intermolecular reaction for the aliphatic compounds is the formation of ethyl acetate from ethanol and acetic acid measured under the same conditions (20% ethanol-water, ionic strength 0.4 M) by Storm and Koshland (1972a). The esterification of benzoic acid in methanol at 25° is 290 times slower than that of acetic acid (Kirby, 1972), so this factor is used to correct the EM s, calculated otherwise in the same way, for the hydroxybenzoic acids. For the phenolic acids see notes m and n b Rate constants are in units of dm3 mol-1 s-1 c Storm and Koshland, 1972a d Storm and Koshland, 1972b Bunnett and Hauser, 1965... 

Capon and Walker, 1974. The reference intermolecular reaction is the phenoxide-catalysed mutarotation of the 6-O-phenoxy-compound, corrected for pX,... 

Unfortunately, in many cases the reaction is not so straightforward it becomes complicated because of the nature of the activated component. There is another nucleophile in the vicinity that can react with the electrophile namely, the oxygen atom of the carbonyl adjacent to the substituted amino group. This nucleophile competes with the amine nucleophile for the electrophilic center, and when successful, it generates a cyclic compound — the oxazolone. The intermolecular reaction (path A) produces the desired peptide, and the intramolecular reaction (path B) generates the oxazolone. The course of events that follows is dictated by the nature of the atom adjacent to the carbonyl that is implicated in the side reaction. 

Imipenem (5.46) has not completely fulfilled such expectations [122], Indeed, this compound is unstable in both acidic and alkaline media. In weakly acidic solutions, imipenem undergoes complex oligomerization, a reaction initiated by the intermolecular attack of the carboxy group on the /3-lactam Fig. 5.17) and yields, finally, a diketopiperazine compound. In weakly alkaline solution, an intermolecular reaction between the /3-lactam and (iminome-thyl)amino group was observed Fig. 5.18). This reaction proceeds via an unstable dimer that breaks down to thienamycin (5.45) and a /3-lactam ring-opened compound bearing a Ai-formyl group [123],... 

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