C-Alkylation intramolecular

The C alkylation has been rationalized 33) by initial N alkylation of 16 to 17 followed by an intramolecular rearrangement involving a six-membered... 

C-Alkylation has also been observed in intramolecular reactions where the O-alkylation is not favoured.76 This property has been recently exploited in a stereocontrolled intramolecular cyclization of nitronate of nitro sugar 101 (Scheme 32), that provided the novel bicyclic nitrolactone 102, a synthetic precursor of tripeptide 103, that includes the first reported polyhydroxylated cyclopentane (3-amino acid.77... 

Acceptor-monosubstituted diazomethanes can be further converted into other types of diazo compound. C-Acylation of diazoacetic esters generally requires very reactive acylating agents, such as acid chlorides [969,970] or bromides [971]. C-Alkylations of acyldiazomethanes are best accomplished by metallation followed by treatment with a carbon electrophile [972-977], C-alkylation can also occur without any base if sufficiently electrophilic aldehydes or ketones are used [973,978 -982] or if the alkylation proceeds intramolecularly [983]. 

Among dichloro bis-electrophiles, malonyl chloride with enamine 183b affords pyridone 189, probably resulting from C-alkylation and cyclocondensation followed by aromatization (02T2821). Finally, o-chloro-benzoylchloride leads to C-benzoylation and subsequent intramolecular substitution of the isolable intermediate to yield quinoline 190 (03ARK (is.2)146). 

Cyclopentenone amelation,1 A new method for this reaction involves Pd(0)-directed C-alkylation of 2-mcthyl-1,3-cyclopentanedione or 2-methyl-l,3intramolecular Wittig reaction (equation I). Of special interest, the cyclopentenone 1 can be obtained in optically active form by use of an optically active phosphine. Thus use of (R)-DIOP (4, 273 5, 360- 361 6, 309) leads to 1 as a 70 30 mixture of ( + )- and (-)-enantiomers. Similar results arc obtained with (R)-(-)-methylphenylprop>i-phosphine. 

The base-catalyzed alkylation of oxindoles favors C-alkylation, and O-alkylation is observed with halides only for particularly favorable intramolecular alkylations (B-70MI30614). Triethyloxonium tetrafluoroborate, on the other hand, gives the O-alkylated... 

Diazines other than diketopiperazines can also be prepared on insoluble supports (Table 15.31 see also Figure 3.13 [382]). Most strategies are based on intramolecular nucleophilic substitutions or acylations. Several examples of the solid-phase preparation of quinoxalinones have been reported. In most cases, the compounds have been prepared from support-bound 2-fluoronitrobenzenes according to the strategies outlined in Figure 15.18. Alternatively, a-amino acid esters bound to polystyrene as IV-benzyl derivatives can be N-arylated with 2-fluoronitrobenzene. Reduction of the resulting 2-nitroaniline leads to the formation of quinoxalinones [383]. 1,4-Diazines have been chemically modified by N- or C-alkylation on insoluble supports (Entries 9 and 10, Table 15.31). 

Although metal-olefin complexation can be a source of enandoselection, reactions exploiting this mechanistic motif have not been developed much. Due to the facile enantioface interconversion process, the origin of the enantioselection often reverts back to Type C alkylation (Figure 8E, 1). To transfer chiral recognition of the coordination process to the ee of the product, kinetic trapping of the incipient 7t-allyl complex is required prior to any isomerization process. For this reason, few successful examples have come from the use of more reactive heteroatom nucleophiles (N, O and S) and/or intramolecular reactions. 

C-H functionalization, 10, 121 C-H intermolecular functionalization, 10, 122 C-H intramolecular functionalization, 10, 130 olefin functionalization, 10, 155 /)3-Carbon atoms, C-H bond functionalization activated alkyl groups intermolecularly, 10, 111 activated alkyl groups intramolecularly, 10, 114 alkanes and alkyl units, 10, 102 Carbon-based ligands, alkali metal chemistry, 2, 3 Carbon-based 77-ligands, in molybdenum carbonyls alkenes, 5, 433 alkynes, 5, 435 allenes, 5, 433... 

C-Alkylation of 1,1-enediamines takes place readily when they are treated with electrophilic olefins including a,/ -unsaturated aldehydes, ketones and carboxylic acid derivatives. Primary and secondary 1,1-enediamines usually lead to fused heterocyclic products due to the simultaneous intramolecular cyclocondensation between the amino and the carbonyl groups of the initially formed adducts. 

He and his students developed C-alkylation with quaternary ammonium salts and nucleophilic displacements on such salts, including the stereochemistry. His name is immediately associated with important innovations in the use of polyphosphoric acid for inter- and intramolecular condensations, cyclizations, and functional conversions in organic chemistry. He pioneered the use of boron trifluoride as an efficient catalyst in the Fischer indole synthesis and discovered new reactions of anils, including Diels-Alder reactions. He and his students delineated the requirements for disproportionation of tertiary amines. He developed the synthesis and chemistry of arylboranic acids. One of his fundamental ideas was for the incorporation of sufficient boron into organ-specific drugs that they could then be... 

Path a can be considered as a C-alkylation by the Mannich base of enamine or enol derivatives the latter acts in the presence, for example, of hydroxylamine, followed by intramolecular condensation leading to ring closure and formation of the aromatic nucleus 340. " By contrast, path b involves amino group replacement by arylamine (N-alkylation by the Mannich base) producing the P-arylaminoketone 341, directly obtainable also by Mannich synthesis. " ... 

Intramolecular alkylation of oximes. Fuchs etal. reasoned that C-alkylation of oximes to give nitroso compounds should be possible when O- or N-alkylation would lead to strained imines. Thus treatment of the oxime tosylate (2) with 1 in a homogeneous reaction results in ring contraction to 3, presumably through a nitrosocyclopropane intermediate a. The reaction with bases insoluble in THF is much slower. 

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