L anhydride

In the synthesis of daminozide an anhydride is used out of necessity rather than out of choice, but it often turns out that there are several alternative reagents all corresponding to the same disconnection. Paracetamol, for example, is an amide that can be disconnected either to amine -I- acyl chloride or to amine -l- anhydride. 

PA-6 (75) or PA-66 or PA-6,66 copolymer/SAN (6-40% AN) (0-25)/ imidized acrylate copolymer with various acid -l- anhydride concentrations (0-25) SSE at 240°C/torque rheometry/DSC/ TEM/mechanical properties/effects of AN content/effects of acid + anhydride concentration/effects of PA amine end-group concentration Majumdar etal. 1994g... 

Aerny, J. (1986a) Diminution de la teneur des vins en anhydride sulfureux I. L anhydride sulfureux et ses proprietes utiles en vinification. Revue Suisse Vitic. Arboric. Hortic. 18, 17-21. 

CisH CltNsO Sj 6-Cblor-3<nitro>benzol sulion 8ft -(l).anhydrid 11122. 

E88 8aure [2-methyl-aiithrachinon>carboi i saiue>(l)]>anhydrid 10 Q 588. 

Essigs iire > [1 -4th oxy - nap hthalin-solfon 84ure> )l-anhydrid 11, 273. 

Fischer, 1906). Similarly heating histidine methyl ester to 100 produces mostly L-anhydride, but also some of the inactive material, which may be either a racemic compound or the tneao form (Pauly, 1910). The mechanism of this racemization is not quite clear it is possible that the ester is unstable, but it is more likely that the basic ester catalyzes the racemization of the anhydride which is being formed in the reaction. 

M.p. 234-235 C. Hydrolyses to aspartic acid. L-asparagine can be prepared from lupin seedlings, and DL-asparagine is synthesised from ammonia and maleic anhydride. L-asparagine is very widely distributed in plants, being found in all the Leguminosae and Gramineae, and in many other seeds, roots and buds. 

CHa CHlCH CHO. Colourless lachrymatory liquid with a pungent odour. B.p. 104 "C. Manufactured by the thermal dehydration of aldol. May be oxidized to crotonic acid and reduced to crolonyl alcohol and 1-butanol oxidized by oxygen in the presence of VjOj to maleic anhydride. It is an intermediate in the production of l-butanol from ethanol. 

L. Treat with hydroxylamine and ferric chloride (pp. 334, 353). Violet or red colorations given particularly by esters. Deep colorations also given by acid chlorides, acid anhydrides and by some acid amides (usually aliphatic) and by a few of the simpler anilides. 

More information has appeared concerning the nature of the side reactions, such as acetoxylation, which occur when certain methylated aromatic hydrocarbons are treated with mixtures prepared from nitric acid and acetic anhydride. Blackstock, Fischer, Richards, Vaughan and Wright have provided excellent evidence in support of a suggested ( 5.3.5) addition-elimination route towards 3,4-dimethylphenyl acetate in the reaction of o-xylene. Two intermediates were isolated, both of which gave rise to 3,4-dimethylphenyl acetate in aqueous acidic media and when subjected to vapour phase chromatography. One was positively identified, by ultraviolet, infra-red, n.m.r., and mass spectrometric studies, as the compound (l). The other was less stable and less well identified, but could be (ll). 

Davies and Warren" found that when 1,4-dimethylnaphthalene was treated with nitric acid in acetic anhydride, and the mixture was quenched after 34 hr, a pale yellow solid with an ultraviolet spectrum similar to that of a-nitro-naphthalene was produced. However, if the mixture was allowed to stand for 5 days, the product was i-methyl-4 nitromethylnaphthalene, in agreement with earlier findings. Davies and Warren suggested that the intermediate was 1,4-dimethyl-5 nitronaphthalene, which underwent acid catalysed rearrangement to the final product. Robinson pointed out that this is improbable, and suggested an alternative structure (iv) for the intermediate, together with a scheme for its formation from an adduct (ill) (analogous to l above) and its subsequent decomposition to the observed product. 

Cydopentane reagents used in synthesis are usually derived from cyclopentanone (R.A. Ellison, 1973). Classically they are made by base-catalyzed intramolecular aldol or ester condensations (see also p. 55). An important example is 2-methylcydopentane-l,3-dione. It is synthesized by intramolecular acylation of diethyl propionylsucdnate dianion followed by saponification and decarboxylation. This cyclization only worked with potassium t-butoxide in boiling xylene (R. Bucourt, 1965). Faster routes to this diketone start with succinic acid or its anhydride. A Friedel-Crafts acylation with 2-acetoxy-2-butene in nitrobenzene or with pro-pionyl chloride in nitromethane leads to acylated adducts, which are deacylated in aqueous acids (V.J. Grenda, 1967 L.E. Schick, 1969). A new promising route to substituted cyclopent-2-enones makes use of intermediate 5-nitro-l,3-diones (D. Seebach, 1977). 

We shall describe a specific synthetic example for each protective group given above. Regiosdective proteaion is generally only possible if there are hydroxyl groups of different sterical hindrance (prim < sec < tert equatorial < axial). Acetylation has usually been effected with acetic anhydride. The acetylation of less reactive hydroxyl groups is catalyzed by DMAP (see p.l44f.). Acetates are stable toward oxidation with chromium trioxide in pyridine and have been used, for example, for protection of steroids (H.J.E. Loewenthal, 1959), carbohydrates (M.L. Wolfrom, 1963 J.M. Williams, 1967), and nucleosides (A.M. Micbelson, 1963). The most common deacetylation procedures are ammonolysis with NH in CH OH and methanolysis with KjCO, or sodium methoxide. 

Trifluoroacetamides are more stable toward nucleophiles than the corresponding esters and are easily formed from trifluoroacetic anhydride and the amine. The trifluoroacetyl group (Tfac) is slowly cleaved by aqueous or methanolic HQ, NH, or Ba(OH)2 solutions as well as by NaBHj in methanol (M.L. Wolfrom, 1967). 

Like butadiene, allene undergoes dimerization and addition of nucleophiles to give 1-substituted 3-methyl-2-methylene-3-butenyl compounds. Dimerization-hydration of allene is catalyzed by Pd(0) in the presence of CO2 to give 3-methyl-2-methylene-3-buten-l-ol (1). An addition reaction with. MleOH proceeds without CO2 to give 2-methyl-4-methoxy-3-inethylene-1-butene (2)[1]. Similarly, piperidine reacts with allene to give the dimeric amine 3, and the reaction of malonate affords 4 in good yields. Pd(0) coordinated by maleic anhydride (MA) IS used as a catalyst[2]. 

A -(2 2-Diethoxyethyl)anilines are potential precursors of 2,3-unsubstituted indoles. A fair yield of 1-methylindole was obtained by cyclization of N-inethyl-M-(2,2-diethoxyethyl)aniline with BFj, but the procedure failed for indole itself[2], Nordlander and co-workers alkylated anilines with bromo-acetaldehyde diethyl acetal and then converted the products to N-trifliioro-acetyl derivatives[3]. These could be cyclized to l-(trifluoroacetyl)indoles in a mixture of trifluoroacetic acid and trifluoroacetic anhydride. Sundberg and... 

The general pattern of alkylation of 2-acylaininothiazoles parallels that of 2-aminothia2ole itself (see Section III.l). In neutral medium attack occurs on the ring nitrogen, and in alkaline medium a mixture of N-ring and N-amino alkylation takes place (40, 43, 161. 163). In acidic medium unusual behavior has been reported (477) 2-acetamido-4-substituted thiazoles react with acetic anhydride in the presence of sulfuric acid to yield 2-acetylimino-3-acetyl-4-phenyl-4-thiazolines (255) when R = Ph. but when R4 = Me or H no acetylation occurs (Scheme 151). The explanation rests perhaps in an acid-catalyzed heterocyclization with an acetylation on the open-chain compound (253), this compound being stabilized... 

In aprotic conditions acetic anhydride sodium acetate induces formation of a fused ring through an intra molecular condensation. It results in a pyrrolo[2,l-fc]thiazole (39), which constitutes an interesting intermediate for the synthesis of dyes (Scheme 18) (40). 

Anilino vinyl derivatives of thiazolium (30, R = H) or acetanilido (30, R = C0CH3), as well as formyl methylene 30b (methods E-G), give asymmetrical dyes when condensed with a methyl reactive group of another species (Scheme 42). Mesosubstituted symmetrical or unsymmet-rical thiazolocyanines are obtainable via /S-alkylmercaptovinyl thiazolium derivatives (32) (methods H and I) (Scheme 43). a or /S carbon atoms of the trimethine chain can be substituted by acetyl when a dye is treated with acetic anhydride (method L). The hydrolysis of neocyanines lead to trimethine cyanine by fractional elimination of a composant chain (method K). 

Hexamethine neutrocyanines are obtained by heating 2-(6-acetanilido-l,3,5-hexatrienyl)-4-arylthiazolium with ketomethylene and sodium acetate in acetic anhydride (69). 

Phenyl-5-thiazolyl)acetic acids variously substituted in the 2-position give the corresponding naphtho[l,2]thiazoles in the presence of acetic anhydride and sodium acetate (397, 426, 857). 

P4ALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) 9a,21-dichloro-17-[(2-furanyl-carbonyl)oxyl]-llb-hydroxy-16a-methyl-pregna-l,4-diene-3,20-dione. See Mometasone fluroate. 

EIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) L-5-Vinyl-2-thioxazolidinone... 

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