Propanes, alkyl-substituted—

Alkyl substituted dinitropentanes. There are two such compds of interest 1,2-Dinitro-2-Methyl-Propane. See Vol 5, D1391-R and Vol 2, B368-R where it is described as Dinitro-iso-butane The Sodium salt of 1,1-Dtnitro-2 Methoxy-Pentene. CH3.CH2.CH2.CH(0CH3).C.(Na)(N02)2,... 

Salaun and de Meijere s groups have applied successfully the intramolecular PKR on 1-cyclopropylidene-1,6-enynes 421-426 (Table 34) [108], accessible via the Pd(0) catalysed alkylation of stabilized carbanions with 1-vinylcyclo-propanes 1-substituted with leaving groups [3a, 109]. 

Other Reactions at the Carbonyl Carbon Atom.— Acetal formation from 3-oxo-steroids in anhydrous alcohols is far more effective than was previously realised. C.d. studies revealed almost quantitative conversion of 5a- or 5 -3-oxo-steroids in methanol into their 3,3-dimethoxy-derivatives, and ethanol or propan-2-ol also gave considerable proportions of the corresponding acetals. Contrary to earlier belief, even the hindered 2-oxo-group gave the 2,2-dimethoxy-derivative (73 % at equilibrium). Acetal formation was drastically reduced by traces of water, however, or by alkyl substitution adjacent to the oxo-group. 

The same is true for alkyl-substituted methylenecyclopropanes, such as butylidenecyclo-propane, which reacts with norbornene to give a modest 34% yield of 4-butylidene-tricyclo[5,2.1.0 ]decane after 3 hours at 95"C in the presence of bis(j7" -cycloocta-l,5-diene)nickel(O) as catalyst. ... 

Fragmentation processes of photoinitiators form a number of volatile products, which may contribute to indoor air pollution. Benzaldehyde and alkyl-substituted benzalde-hydes are usual components, because Norrish-I is the most important reaction for cleavage. Awell known example is l-phenyl-2-hydroxy-2-methyl-propane-l-one (PHMP). a-Cleavage generates two radicals in the first step. The benzoyl radical may recombine to form benzil, reduction of PHMP leads to l-phenyl-2-methy 1-1,2-propane and acetone, and recombination of the 2-hydroxypropyl radical gives 2,3-dimethyl-2,3-butanediol... 

Whenever syn- and anti-isomers are possible, they are al>vays formed in equal yields. On the practical side, these alkyl-substituted fluorocyclo-propanes have been synthesized, trapped, and used for the purposes of finding out their retention times in various GC columns (55). 

Major new insights into the electronic effects of substituents have resulted from measurements conducted in the gas phase, where the effects of solvent are eliminated. DePuy and co-workers determined the order of acidity to be ethane < propane (2° hydrogen atoms) < methane < isobutane (3° hydrogen atom) in the gas phase. This rather surprising result that methane is more acidic than ethane has some support in theoretical calculations. Therefore, the effect of alkyl substitution on a carbanion in solution may be better described as a solvation effect. As le Noble put it ... 

Disubstituted-1,3,2-dioxaborinanes, 4.5, are structurally similar to 2,5-disubsti-tuted-1,3-dioxanes but without the complication of cis-/fra s-isomerism the creation of the dioxaborinane ring is achieved by esterification of a 2-substituted-propan-1,3-diol with an arylboronic acid [62, 63]. For compounds of this type with a 5-aryl substituent, 2-arylpropan-l,3-diols are required and are prepared by coupling the ethyl cyanoacetate anion and a 4-substitut-ed-phenyl bromide or iodide [62] and the 5-alkyl-substituted-1,3,2-dioxaborinanes [63] are obtained from 2-alkylpropan-1,3-diols (4.1). 

Abbreviations acac, acetylacetonate Aik, alkyl AN, acetonitrile bpy, 2,2 -bipyridine Bu, butyl cod, 1,5- or 1,4-cyclooctadiene coe, cyclooctene cot, cyclooctatetraene Cp, cyclopentadienyl Cp, pentamethylcyclopenladienyl Cy, cyclohexyl dme, 1,2-dimethoxyethane dpe, bis(diphenyl-phosphino)ethane dppen, cis-l,2-bis(di[Atenylphosphino)ethylene dppm, bis(diphenylphosphino) methane dppp, l,3-bis(diphenylphosphino)propane eda,ethylenediamine Et,ethyl Hal,halide Hpz, pyrazole HPz, variously substituted pyrazoles Hpz, 3,5-dimethylpyrazole Me, methyl Mes, mesityl nbd, notboma-2,5-diene OBor, (lS)-endo-(-)-bomoxy Ph, phenyl phen, LlO-phenanthroline Pr, f opyl py, pyridine pz, pyrazolate Pz, variously substituted pyrazolates pz, 3,5-dimethylpyrazolate solv, solvent tfb, tetrafluorobenzo(5,6]bicyclo(2.2.2]octa-2,5,7-triene (tetrafluorobenzobanelene) THE, tetrahydrofuran tht, tetrahydrothicphene Tol, tolyl. 

Sanders et al. (1999) attempted to lower the melting points of aromatic polyanhydrides by substituting branched alkyl groups in place of the linear alkyls of P(CPP-SA). They synthesized poly[l,2-bis(/ -carboxyphenoxy)-propane-co-sebacic acid] (P(1,2-CPP-SA)), poly[l,3-bis(/ -carboxyphenoxy)-2-methyl propane-co-sebacic anhydride] (P(CPMP-SA)), and poly[l,3-bis (/ -carboxyphenoxy)-2,2-dimethyl propane-co-sebacic anhydride] (P(CPDP SA)), all of which had melting points below 165°C. 

Examples of the so-called chaperon effect involving interaction between the electrophile and an appropriate substituent at the a-position in an alkyl chain prior to ring substitution at the ortAo-position have been explored in nitrations involving dilute solutions of nitric acid in dichloromethane. Aldehydic or ketonic carbonyl groups are most effective, but carboxyl, alkoxycarboxyl, and amide groups also work well. l-Phenylpropan-2-one, for example, forms 85% of l-(2-nitrophenyl)propan-2-one (5). 

The title compound can be prepared by condensing an alkyl a-bromocaprylate with a trialkyl propane-1,1,3-tricarboxylate to give a substituted cyclopentanone. Hydrolysis, decarboxylation, and esterification of the resulting monocarboxylic... 

Added CO2 allows the synthesis of substituted maleic anhydrides. According to a novel aminomethylation, ethane or propane is reacted with /V./V-di alkyl methyl-amine A-oxides in the presence of trifluoroacetic acid and a catalytic amount of Cu(OAc)2 to afford A,A-dialkylaminomethylated alkanes in good yields 321 337 338... 

However, the most important approach to 2-substituted dihydro-1,3-oxazines involves the acid-promoted condensation of alkyl nitriles and propane-1,3-diols, carbonium species (200) are assumed to be intermediates in this reaction, being formed preferentially from the more highly substituted position of the diol (Scheme 87) (57JOC11). 

Although we discussed its mechanism at length in Section 4-3, free-radical halogenation is rarely an effective method for the synthesis of alkyl halides. It usually produces mixtures of products because there are different kinds of hydrogen atoms that can be abstracted. Also, more than one halogen atom may react, giving multiple substitutions. For example, the chlorination of propane can give a messy mixture of products. 

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