L A-substituted

Cyclization of l-(A -substituted aminocarbonyl)-3-[(tert-butoxycarbonyl) amino]- and -3- [Ai -(tert-butoxycarbonyl)tryptophyl]amino -2-(ethoxycar-bonylmethyl)piperidines (e.g. 188) on the action of NaH gave 2-substituted 5-(substituted amino)perhydropyrido[l,2-c]pyrimidine-l,3-diones (e.g. 159 and 189) (97JMC3402, 97MIP16, 98MI63, 0UMC2219). Cyclization could be also carried out in the presence of DBU (01JMC2219). 

Moskva, V.V., Nazvanova, G.F., Zykova, T.V, Razumov, A.L, and Chemodanova, L.A., Substituted vinylphosphonic derivatives. Part 10. (2-Alkoxy-l-alkylvinyl)-phosphonic and -phosphonothioic derivatives, Zh. Obshch. Khim., 41, 1680, 1971 J. Gen. Chem. USSR (Engl. Transl.), 41, 1687, 1971. 

Tin.—A review on the chemistry of compounds containing the Sn—bond contains some mechanistic material. The formation of Ph2SnL2 from Ph2SnCl2 and L (L=a substituted 8-quinolate ion) has been studied kinetically in DMSO solution. Different rate laws are observed for the parent compound (8) and its 2-methyl derivative (9). Steric effects are suspected as the cause of the difference. ... 

Acyl ylides add to N =sN double bonds of azo compounds giving rise to the formation of l-A(-sub-stituted alkylidenephosphoranes (e.g. equation 29). It should be mentioned that l-A(-substituted ylides, which carry only hydrogen or alkyl groups at the nitrogen, are unknown. 

Resonance Raman spectroelectrochemistry was used to probe the formation of radical anion species from Re(I) and Cu(I) complexes of dipyrido[3,2-a 2, 3 -c]-phenazine and related complexes, e.g. (46). Similar studies were used to probe electron distributions in reduced forms of Re(CO)3Cl(L), where L = a substituted quinoxaline. Resonance Raman, TR and TRIR experiments were used to characterise MLCT excited states of [ 4,4 -(X)2bipy (CO)3Re (4,4 -bipy)R-e (CO)3 4,4 -(X)2bipy ], where X = H or CH3. The IR spectrum of mw5 -[Re(PPh3)2(Pc )] contained Pc bands showing the presence of Re(II).2i6... 

In the reaction of a substituted ylide (r CH—PPh ) with an aldehyde R CHO, a stereochemical problem arises. Much work has been carried out in order to achieve control of either cis- or rrans-alkene formation. This work has been reviewed several times with always changing viewpoints (A. Maercker, 1965 L.D. Bergelson, 1964 M. Schlosser, 1970 H. Best-mann, 1979). 

Direct 3-silylation of A -substituted indoles has been ellected by reaction of the indoles with trimethylsilyl triflate in the presence of triethylamine[12]. The trimethylsilyl group has also been introduced via 3-lithio-l-(phenylsulfonyl)-indole[13]. 

Reactions. Heating an aqueous solution of malonic acid above 70°C results in its decomposition to acetic acid and carbon dioxide. Malonic acid is a useful tool for synthesizing a-unsaturated carboxyUc acids because of its abiUty to undergo decarboxylation and condensation with aldehydes or ketones at the methylene group. Cinnamic acids are formed from the reaction of malonic acid and benzaldehyde derivatives (1). If aUphatic aldehydes are used acryhc acids result (2). Similarly this facile decarboxylation combined with the condensation with an activated double bond yields a-substituted acetic acid derivatives. For example, 4-thiazohdine acetic acids (2) are readily prepared from 2,5-dihydro-l,3-thiazoles (3). A further feature of malonic acid is that it does not form an anhydride when heated with phosphorous pentoxide [1314-56-3] but rather carbon suboxide [504-64-3] [0=C=C=0], a toxic gas that reacts with water to reform malonic acid. 

CuSO added if Cu is <400 mg/L. a-Nitroso-(3-naphthol maybe substituted for Sb to precipitate Co. 

Chemical antiozonants comprise the second general class of commercial antiozonants. Of the many compounds reported to be chemical antiozonants, nearly all contain nitrogen. Compound classes include derivatives of l,2-dihydro-2,2,4-trimethylquinoline, A/-substituted ureas or thioureas, substituted pyrroles, and nickel or zinc dithiocarbamate salts (see also Antioxidants). The most effective antiozonants, however, are derivatives of -phenylenediamine... 

A Substituted-l-Amino-4-hydroxyanthraquinones. These dyes show good affinity and hghtfastness and give violet to blue shades. However, the sublimation fastness is in general not satisfactory. An example is Cl Disperse Blue 72 [81-48-1] (117) (Cl 60725), prepared from leucoquinizarin and -toluidine. 

Palladium and Palladium Alloys. Palladium is used in telephone equipment and in electronics appHcations as a substitute for gold in specific areas. Palladium is plated from ammoniacal and acid baths available along with chelated variations as proprietary processes. One typical alkaline bath uses 8 g/L diammine-dinitropalladium, 100 g/L ammonium nitrate, and 10 g/L sodium nitrite. The pH is adjusted to 9—10 using ammonium hydroxide, and the bath is operated at 100 A/m at 50° C. If ammonium sulfamate, 100 g/L, is used in some baths to replace the nitrate and sodium nitrite salts, the bath is mn at lower temperature, 25—35°C, and a pH of 7.5—8.5. A palladium—nickel alloy, 75% Pd, is plated from a bath having 6 g/L palladium from the same salt, 3 g/L nickel from nickel sulfamate concentrate, and 90 g/L ammonium hydroxide. The bath is operated at 20—40°C with 50-100 A/m/... 

Fig. 5. Proposed mechanism of iaactivation of a-chymotrypsia by the pseudoirreversible inhibitor 2-ethoxy-4Ff-3,l-benz-oxazia-4-one. A substituted...

Hydrolysis of Enol Esters. Enzyme-mediated enantioface-differentiating hydrolysis of enol esters is an original method for generating optically active a-substituted ketones (84—86). If the protonation of a double bond occurs from one side with the simultaneous elimination of the acyl group (Fig. 3), then the optically active ketone should be produced. Indeed, the incubation of l-acetoxy-2-methylcyclohexene [1196-73-2] (68) with Pichia... 

A-Substituted pyrroles, furans and dialkylthiophenes undergo photosensitized [2 + 2] cycloaddition reactions with carbonyl compounds to give oxetanes. This is illustrated by the addition of furan and benzophenone to give the oxetane (138). The photochemical reaction of pyrroles with aliphatic aldehydes and ketones results in the regiospecific formation of 3-(l-hydroxyalkyl)pyrroles (e.g. 139). The intermediate oxetane undergoes rearrangement under the reaction conditions (79JOC2949). 

The palladium-promoted conversion of 1,3-dienes to pyrroles proceeds via 4-acetoxy-2-alkenylpalladium complexes (Scheme 50g) (81CC59), and a similar pathway may be involved in the palladium mediated reaction of but-2-ene-l,4-diol with primary amines to give A-substituted pyrroles (74CC931). 

Together with pyridones, the tautomerism of pyrazolones has been studied most intensely and serves as a model for other work on tautomerism (76AHC(Sl)l). 1-Substituted pyrazolin-5-ones (78) can exist in three tautomeric forms, classically known as CH (78a), (DH (78b) and NH (78c). In the vapour phase the CH tautomer predominates and in the solid state there is a strongly H-bonded mixture of OH and HN tautomers (Section 4.04.1.3.1). However, most studies of the tautomerism of pyrazolones correspond to the determination of equilibrium constants in solution (see Figure 20). 

In a neutral azole, the apparent rate of formation of an A-substituted derivative depends on the rate of reaction of a given tautomer and on the tautomeric equilibrium constant. For example, with a 3(5)-substituted pyrazole such as (199), which exists as a mixture of two tautomers (199a) and (199b) in equilibrium, the product composition [(200)]/[(201)] is a function of the rate constants Ha and fcs, as well as of the composition of the tautomeric mixture (Scheme 16) <76AHC(Si)l). 

The photodecomposition of 2,1-benzisoxazolium salts gave iV-substituted phenones (Scheme 22). In one case the l-(adamantyl)-3-phenyl-2,l-benzisoxazolium cation (51) did not generate a substituted phenone with reductive ring substitution. Rather, adamantyl ring rupture occurred to produce (52) (Scheme 22) (78JOC123.3, 77JOC3929). 

O-Alkylation of A-unsubstituted /3-lactams to give the corresponding 2-alkoxy-l- etines can be achieved by reaction of the azetidin-2-ones with hard electrophiles (trialkyloxonium tetrafluoroborates) followed by treatment with base (cf. Section 5.09.4.3.1) (67JHC619, 69LA(725)124). In contrast, reaction of the A-unsubstituted azetidin-2-ones (73) or their derived anions with a variety of softer electrophiles results in A-substitution, and some representative reactions are illustrated in Scheme 7. 

Reduction of Order If one homogeneous solution, say, can be found by inspection or otherwise, an equation of lower order can be obtained by the substitution = yju,. The resultant equation must be satisfied by = constant or Ai = 0. Thus the equation will be of reduced order if the new variable L/ = A y,/ul) is introduced. 

This is an old, familiar analysis that applies to any continuous culture with a single growth-limiting nutrient that meets the assumptions of perfect mixing and constant volume. The fundamental mass balance equations are used with the Monod equation, which has no time dependency and should be apphed with caution to transient states where there may be a time lag as [L responds to changing S. At steady state, the rates of change become zero, and [L = D. Substituting ... 

Ganellin and Ridley subsequently showed that this reaction was of wide applicability and could be applied to the synthesis of tryptamine (23) itself and a number of indole derivatives with 3-(S-mono- or 3- -dialkylaminoalkyl side chains where the side chain contained two or more carbon atoms.A number of compounds of this general type including 79, 80, 81, 82, 83, 84, 85, and 86 have been prepared by these authors. Trace quantities of the corresponding l-(/8-dialkylaminoethyl)indole derivatives were formed atthe same time as other isomers. However, only the A-substituted product. 

Anhydro-bases derived from quaternary )S-carbolinium salts are reduced to p /r-A-substituted-l,2,3,4-tetrahydro-j8-carboline derivatives on hydrogenation over Adams catalyst in methanol solution made alkaline to ensure the presence of anhydro-base. ... 

The least squares value for the p constant obtained by this procedure is +6.2 it wiU be obviously subject to change as more meta and epi substituents become available. Only the cata-NO group was excluded from the above plot because it causes a strongly enhanced resonance effect in nucleophilic substitution (Section IV,C, l,a) and an anomalous effect of uncertain origin in the dissociation of carboxylic acids. It can be assumed that the reaction constant for 4-chloro-... 

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