摘要:

Abstract2‐Alkylamino‐ or arylaminopyridines react directly with α‐bromoketones to afford 1‐alkyl‐ or 1‐arylimidazo[1,2‐a]pyridinium salts with substituents at position 2. Use of chloroacetaldoxime as the quaternizing agent yields (after hydrolysis) the imidazo‐[1,2‐a]pyridinium ion with no substituent at position 2. The earlier supposition that alkylation of imidazo[1,2‐a]pyridines occurs in position 1 has been shown to be correct.It has been pointed out that the 1‐substituted imidazo[1, 2‐a]pyridinium system is but one of a group of aromatic heterocyclic systems isoelectronic with

ISSN:0022-152X    

DOI:10.1002/jhet.5570020401

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractThe inhibition of dihydrofolic reductase by twenty appropriately 1‐substituted‐4, 6‐diamino‐1, 2 ‐ dihydro‐2, 2‐dimethyl‐s‐triazines were compared in order to shed light on the mode of phenyl binding of 1‐aryl‐1,2‐dihydro‐s‐triazines. When the 1‐phenyl group was substituted by a cationic group at the 4‐position or an anionic group at either the 3‐ or 4‐position, a large loss in affinity by the enzyme for the resultant inhibitor was noted. This loss in affinity is best explained by the concept that the 1‐aryl group complexes with a hydrophobic region on the enzyme and that the hydrophobic region repels any aryl group bearing either a positively or negatively charged group.p‐Substituents coplanar with the 1‐aryl group caused a steric interaction with the enzyme resulting in considerable loss in binding to this enzyme isolated from pigeon liver; this steric effect was considerably less in them‐position. Inductive effects of 1‐phenyl substituents on a possible charge‐transfer complex of the 1‐aryl group or on the binding ability of the 4,6‐diamino‐1,2‐dihydro‐s‐triazine ring system could not be correlated with the Hammett sigma‐values; ther

ISSN:0022-152X    

DOI:10.1002/jhet.5570020402

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractFour different routes to 6‐alkyl‐, 6‐aryl‐, and 6‐aralkyl‐2,4‐diamino‐s‐triazines were investigated. The most convenient was reaction of an ester with biguanide in methanol at room temperature. Seven of these 6‐substituted 2,4‐diamino‐s‐triazines were investigated as inhibitors of dihydrofolic reductase. As a class they were weaker inhibitors than the corresponding 2,4‐diamino‐6‐substituted pyrimidines, this difference being attributed to the weaker basicity of the former class. Although hydrophobic bonding by 6‐alkyl and 6‐aralkyl groups on 2 the 4‐diamino‐s‐triazine system could be detected, the extent of hydrophobic bonding was much weaker than that previously seen with 2,4‐diaminopyrimidine containing a 5‐alkyl or 5‐aralkyl group or 1‐alkyl‐ and 1‐ara

ISSN:0022-152X    

DOI:10.1002/jhet.5570020403

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractThirteen 5‐alkyl ‐ 2, 4 ‐diamino ‐ 6 ‐ pyrimidinols have been compared as inhibitors of dihydrofolic reductase in an attempt to delineate some of the conformational requirements for hydrophobic bonding to the enzyme; definite conformational limitations were observed. For example, cyclohexyl andtrans‐crotyl side‐chains gave inhibitors that were as effective as then‐butyl‐6‐pyrimidinol, whereas, isoamyl was better than all three; these results indicate that then‐butyl group complexes in a near‐staggered conformation and additional hydrophobic bonding can be obtained by branching at C3of the butyl group. Methyl branching at C2of then‐butyl group also gave a better inhibitor thann‐butyl, but the 2‐methylbutyl side‐chain was only half as effective as isoamyl; in contrast, the 1‐methylbutyl side‐chain gave an inhibitor only one‐half as effective asn‐butyl. That the amount of hydrophobic bonding was simply an “extraction process” dependent upon the size of the hyd

ISSN:0022-152X    

DOI:10.1002/jhet.5570020404

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

Abstract1,2,3‐Thiadiazole‐4‐carboxylic acid (IV) has been synthesized by oxidation of 5‐(2‐furyl)‐1,2,3‐thiadiazole‐4‐carboxylic acid (IIb), and convertedviathe acid chloride (V) to the amide (VI), ethyl ester (VII) and azide (IX). Rearrangement of the azide (IX) in ethanol led to ethyl N‐(1,2,3‐thiadiazol‐4‐yl)carbamate (X) and in benzene or toluene to a complex substance, possibly N,N,N‐tris‐(1,2,3‐thiadiazol‐4‐yl)‐isocyanurate (XI). Ethyl 5‐phenoxy‐1,2,3‐thiadiazole‐4‐carboxylate (XIII), prepared from ethyl (phenoxy‐acetyl)diazoacetate (XII), has been converted to ethyl 5‐formyl‐1,2,3‐thiadiazole‐4‐car‐boxylate methyl phenyl acetal (XVI)viathe α ‐halo ether (XIV). The acetal (XVI) underwent partial hydrolysis in dilute acid to yield ethyl 5‐formyl‐1,2,3‐thiadiazole‐4‐car‐boxylate phenyl hemiacetal (XVII) as an oil. Vacuum distillation of XVII gave ethyl 5‐formyl‐1,2,3‐thiadiazole‐4‐carboxylate (XVIII) as an oil. The aldehyde X

ISSN:0022-152X    

DOI:10.1002/jhet.5570020405

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractIn the course of investigating the preparation of acis‐decahydroazulene (bicyclo‐[5.3.0]decane) ring system, a dioxa analog was synthesized as a model compound. This paper describes the preparation of the hitherto unknown heterocyclic system cis,cis‐4, 8‐dimethyl‐cis‐2, 6‐dioxadecahydr

ISSN:0022-152X    

DOI:10.1002/jhet.5570020406

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractThe compounds obtained from the reactions of phenyl salicylate and 2‐hydroxybenzo‐phenone with phosphorus pentachloride have been shown to have structures I A and II A, respectively, rather than alternative heterocyclic structures on the basis of the comparison of the P31chemical shifts with appropriate reference compounds and additional chemical evidence. Compound I reacts with two equivalents of phenol in the presence of two equivalents of triethylamine to form mainly compound VIII (substitution on phosphorus). Structure VIII is confirmed via P31n.m.r. and IR spectra and the fact that partial hydrolysis forms the same compound (VII) that is obtained from the reaction of compound III with phenol (only phosphorus substitution possible). A mechanism with initial reaction of phosphorus pentachloride (as tetrachlorophosphonium ion) on the phenolic hydroxyl is postulated on the basis of the available evidence. The P31chemical shifts for compounds XIV A and XV A confirm these structures as heterocyclic in accord with previous chemical evidence. Structure XIV A is of historical importance as one of the first three cyclic structures ever published in the classical paper in which Couper announced his structural theory of organic chemis

ISSN:0022-152X    

DOI:10.1002/jhet.5570020407

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractSeveral 2‐pyridylmethylene‐1‐indanones (I) were prepared and reduced to 2‐pyridyl‐methyl‐1‐indanones (II). The reductive cyclization of 5, 6‐dimethoxy‐ and 6‐hydroxy‐5‐methoxy‐2‐pyridylmethylene‐1‐indanone gave the corresponding 5a, 6, 6a, 7, 8, 9, 10, 11a‐octa

ISSN:0022-152X    

DOI:10.1002/jhet.5570020408

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractThe physical and spectral properties of five previously undisclosed diazirines substituted with electron‐withdrawing groups are described. The halo‐diazirines yield the respective divalent carbon species and nitrogen on pyrolysis. The cyanofluoro‐, fluoro‐methoxy‐ and fluorodifluoramino‐carbenes form the respective cyclopropanes with tetra‐fluoroethylene. The intramolecular reactions of difluoramino‐substituted carbenes are also discussed. The ultraviolet spectr

ISSN:0022-152X    

DOI:10.1002/jhet.5570020409

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY

摘要:

AbstractTreatment of 4‐oximino‐4‐phenylbutyric acid with dicyclohexylcarbodiimide gave 6H‐3‐phenyl‐4, 5‐dihydro‐6‐oxo‐1, 2‐oxazine (IId), which was characterized by its infrared spectrum and some reactions. Ring cleavage of IId was easily accomplished by acid or base such as hydrochloric acid, alcohol or amines. The treatment of 4‐oximino‐valeric acid with dicyclohexylcarb

ISSN:0022-152X    

DOI:10.1002/jhet.5570020410

出版商:Wiley‐Blackwell    

年代:1965

数据来源: WILEY