Anhydrides, cyclization

Disubstituted phthalic anhydrides cyclize to form phthalocyanines, e.g. 7 from 6. 

The starting material is succinic dialkylester, which is easily obtained from maleic anhydride. Cyclization is accomplished with sodium alcoholate in a high boiling solvent or solvent mixture (such as diphenylether/diphenyl) to afford the succinylosuccinic dialkylester 54 ... 

Acetic anhydride cyclization of the 2-hydroxyphenyl-3,4-dihydro-quinoxaline 79 yields the benzopyranoquinoxaline derivative 80.95 Some l,2-dihydro-2-arylquinoxalines have herbicidal activity.96... 

VB V VjO, Oxidation of hydrocarbons Butene to maleic anhydride BcnEcne to pthalic anhydride Cyclization of C% to Cj paraffins... 

IA and O-substituted hydroxylamines (131) give anthranilic acid hydrox-ylamides (132)96 (hydroxylamine itself forms the O-acyl derivative95). Carboxylic acids and anhydrides cyclize 132 to the quinazolones 13396 (Eq. 14). 

Myrtenol (203 X = CH2OH) may be obtained most efficiently from the more stable secondary allylic alcohol (+)-trans-pinocarveol (30 enantiomer) via bromination with PBra to the rearranged bromide (203 X = CH2Br) [(30) (203 X = CH20H)/85 15] ester thermolysis and isomerization-oxidation were less effective, and the direct acid-catalysed isomerization was not observed. Intramolecular cyclization of (206), which is readily synthesized via trifluoroacetic anhydride cyclization of 4-methylcyclohex-3-enylacetic acid to (186), affords (207) which is cleaved to (208 X = NH2) in a synthesis of ( )-a-... 

Cyclization The dione (1) is converted into the estrane (2) by acetyl p-toluenesulfonate in acetic anhydride. Cyclization of (1) by the usual reagents is accompanied by dehydration. Thus cyclization of (3), which lacks a Cn-keto group, gives (4). 

Intramolecular acylations are quite common. The normal Friedel-Craf ts procedure involving an acid halide and Lewis acid is frequently used, but there are alternatives. One useful method for inducing intramolecular acylations is to dissolve the carboxylic acid in polyphosphoric acid and heat to effect cyclization. The mechanism probably involves formation of a mixed carboxylic-phosphoric anhydride. Cyclizations of this type can also be carried out using polyphosphate ester, ... 

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). 

Unusual cyclocarbonylation of allylic acetates proceeds in the presence of acetic anhydride and an amine to afford acetates of phenol derivatives. The cinnamyl acetate derivative 408 undergoes carbonylation and Friedel-Crafts-type cyclization to form the a-naphthyl acetate 410 under severe condi-tions[263,264]. The reaction proceeds at 140-170 under 50-70 atm of CO in the presence of acetic anhydride and Et N. Addition of acetic anhydride is essential for the cyclization. The key step seems to be the Friedel-Crafts-type cyclization of an acylpalladium complex as shown by 409. When MeOH is added instead of acetic anhydride, /3,7-unsaturated esters such as 388 are... 

The cyclohexadiene derivative 130 was obtained by the co-cyclization of DMAD with strained alkenes such as norbornene catalyzed by 75[63], However, the linear 2 1 adduct 131 of an alkene and DMAD was obtained selectively using bis(maleic anhydride)(norbornene)palladium (124)[64] as a cat-alyst[65], A similar reaction of allyl alcohol with DMAD is catalyzed by the catalyst 123 to give the linear adducts 132 and 133[66], Reaction of a vinyl ether with DMAD gives the cyclopentene derivatives 134 and 135 as 2 I adducts, and a cyclooctadiene derivative, although the selectivity is not high[67]. 

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... 

Hydroxvthiazolium hydroxide inner salts (2) (X = 0) have been synthesized by an improved acetic-anhydride-triethylamine-caialyzed cyclization of N-substituied N-thiobenzovlalanines (Scheme 15) (23). 

Fig. 2. Cyclization of amic acid to imides or isoimides via (12). Formation of the mixed anhydride intermediate (12) is shown in text.

Diallyl Isophthalate. DAIP polymerizes faster than DAP, undergoes less cyclization, and yields cured polymers of better heat resistance, eg, up to ca 200°C. Prepolymer molding materials such as Dapon M of EMC, are not sticky. Maleic anhydride accelerates polymerization, whereas vinyl isobutyl ether retards it and delays gelation in castings. Copolymers with maleic anhydride are exceptionally hard and tough and may scratch homopolymer surfaces. 

Fig. 2. Synthesis of uma2enil (18). The isonitrosoacetanihde is synthesized from 4-f1iioroani1ine. Cyclization using sulfuric acid is followed by oxidization using peracetic acid to the isatoic anhydride. Reaction of sarcosine in DMF and acetic acid leads to the benzodiazepine-2,5-dione. Deprotonation, phosphorylation, and subsequent reaction with diethyl malonate leads to the diester. After selective hydrolysis and decarboxylation the resulting monoester is nitrosated and catalyticaHy hydrogenated to the aminoester. Introduction of the final carbon atom is accompHshed by reaction of triethyl orthoformate to...

The need for pyrazoles substituted with the trifluoroacetyl group led to the reaction of ethoxyvinyl ether with trifluoroacetic anhydride, yielding 4-ethoxy-l,l,l-trifluoro-3-buten-2-one (38) this further reacted with aldehyde / fZ-butyUiydrazones, and after cyclization at room temperature under mildly acidic conditions the pyrazoles were obtained in satisfactory yields (eq. 7). Further treatment with H2SO4 removed the tert-huty group, thus providing an opportunity for further derivatization at N. ... 

The Frasca method for obtaining 1-arylindazoles also involves a C(3)—C(3a) ring closure (67CJC697). It consists in the cyclization of p-nitrophenylhydrazones of ketones and aldehydes with polyphosphoric acid. The Barone computer-assisted synthetic design program has found several new methods for preparing indazoles (79MI40409). The selected method involves the transformation of jV, jV -diphenylhydrazides (596) into 1-phenylindazoles (597) by means of trifluoromethanesulfonic anhydride. The yields vary from 2% (R = H) to 50% (R = Ph). 

The electrochemical reduction of 3-nitrophthalic acid at controlled potentials gave 2,1-benzisoxazole-3-carboxylic acid. Cyclization is presumed to proceed via an intermediate oxime (67AHC(8)277). Treating 5-iodoanthranilic acid with acetic anhydride gave 3-acetoxy-5-iodo-2,l-benzisoxazole (596) (65JMC550). 

Styryl sulfonyl chloride Friedel-Crafts cyclization benzo[h]thiophenes from, 4, 873 Succinic anhydrides polymers, I, 277 mass spectrometry, 4, 585 structure, 4, 552... 

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