ISSN:0018-019X    

DOI:10.1002/hlca.19730560102

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractAllyl aryl ethers which have no strongly electron attracting substituents undergo a charge‐induced [3 s, 3 s] sigmatropic rearrangement in the prescence of 0.7 mole boron trichloride in chlorobenzene at low temperature, to give after hydrolysis the correspondingo‐allyl phenols (Tables 1 and 2). The charge induction causes an increase in the reaction rate relative to the thermalClaisenrearrangement of ∼1010. With the exception of allyl 3‐methoxyphenyl ether(5),m‐substituted allyl aryl ethers show similar behaviour (with respect to the composition of the product mixture) to that observed in the thermal rearrangement (Table 3). The rearrangement of allyl aryl ethers with an alkyl group in theo‐position, in the prescence of boron trichloride, yields a mixture ofo‐ andp‐allyl phenols, where morep‐product is present than in the corresponding product mixture from the thermal rearrangement (Table 4). This ‘para‐effect’ is especially noticeable foro‐alkylated α‐methylallyl aryl ethers (Table 5 ).With boron trichloride, 2,6‐dialkylated allyl aryl ethers give reaction products which arise, in each case, from a sequence of anortho‐Claisenrearrangement followed by a [1,2]‐, [3,3]‐ or [3,4]‐shift of the allyl moiety (Tables 6 and 7). Ally1 mesityl ether (80), with boron trichloride, gives pure 3‐ally1 mesitol (95). From phenol, penta‐ally1 phenol (101) can be obtained by a total of five O‐allylations followed by three thermal and two boron trichloride‐induced rearrangements.The sigmatropic rearrangements of the ethers studied, using D‐ and14C‐labelled compounds, are collected in scheme 2; only the reaction steps indicated by heavy arrows are of importance.With protic acids, there is a [3,3]‐shift of the allyl group in 6‐allyl‐2,6‐disubstituted cyclohexa‐2,4‐dien‐l‐ones, while with boron trichloride the [3,3]‐reaction is also observed along with the much less important [1,2]‐ and [3,4]‐transformations (Table 8). 4‐Allyl‐4‐alkyl‐cyclohexa‐2,5‐dien‐1‐ones give only [3,3]‐rearrangements with boron trichloride (Table 9). As expected, the naphthalenone112, which is formed by allowing boron trichloridc to react for a short time with allyl (1‐methyl‐2‐naphthyl) ether (111), undergoes only a [3,4] rearrangement (Scheme 3).Representations of how, in our opinion, the complex behaviour of allyl aryl ethers and allyl cyclohexadienones under the influence of boron trichloride, can be rationalized are collected together in Schemes 4 and 5.In the last part of the discussion secti

ISSN:0018-019X    

DOI:10.1002/hlca.19730560103

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe rearrangement of 10‐allyl‐2‐oxo‐Δ1(9), 3‐hexahydronaphthalene (12) catalysed by trifluoroacetic acid and otherBronstedacids yielded almost exclusively the [3s, 3s]‐products, 1‐ and 3‐allyl‐5,6,7,8‐tetrahydro‐2‐naphthol (16and15, respectively). The rearrangement of12with trifluoroacetic anhydride or acetic anhydride/sulfuric acid, yields, besides15and16, appreciable amounts of the [1s, 2s]‐rearrangement product, 4‐allyl‐5,6,7,8‐tetrahydro‐2‐naphthol (14) (table 1).The CF3COOH catalysed dienone‐phenol‐rearrangement of 6‐ally‐5,6‐dimethyl‐cyclohexa‐2,4‐dien‐l‐one (11) in hexane at 0° yields4‐allyl‐2,3‐dimethyl‐phenol (19). Rearrangement of d3‐llcontaining a specifically deuteriated allyl group proves that the formation of d3‐19occursviaa [3s, 3s]‐sigmatropic reaction. On the other hand, treatment of11with (CF3CO)2O at 0° in hexane gives (after saponification) 4‐allyl‐, 5‐allyl‐ and 6‐allyl‐2,3‐dimethyl‐phenol (19,20and21, respectivcly). This reaction occursviaan acyloxybenzenium‐ion intermediate. The reactions performed with d3‐11demonstrate that the formation of d3‐19occurs both by a direct [3s, 3s]‐shift and by a twofold [1s, 2s]‐shift, respectively. d3‐20is formcd by a [3s, 4s]‐sigmatropic reaction. d3‐21is obtained with about 95% inversion of the carbon skeleton of the allyl group. Thus d3‐21is mainly formed by a [1s, 2s]‐ followed by a [3s, 4s]‐sigmatropic rearrangement.6‐Allyl‐6‐niethyl‐cyclohexa‐2,4‐dien‐1‐one (4) yields with CF3COOH in hexane 4‐allyl‐2‐methyl‐phenol (5), whereas with (CF3CO)2O in hexane5, 3‐allyl‐ and 5‐allyl‐2‐methyl‐phenol (24and25, respectively) are formed in comparable amounts. As a minor product 6‐allyl‐2‐methyl‐phenol (26) was observed.Based on these observations, the concept of charge‐induced,e.g.schemes 2 and 3, and charge‐controlled,e.g.scheme 7, sigmatropic reactions, has been elaborated. In the former, the charge serves only to accelerate appreciably thermal orbital‐symmetry allowed reactions, whereas in the latter, the charge determines the course of the transformations accor

ISSN:0018-019X    

DOI:10.1002/hlca.19730560104

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractN‐Allyl‐2‐methylaniline (12) forms on heating at 140° in xylene in the presence of zinc chloride 2‐allyl‐6‐methylanline (19) as major compound and 4‐allyl‐2‐methylaniline (20) as well as 2,7‐dimethyl‐indoline (21) as minor products. Compound21is also formed when19is heated in the presence of zinc chloride (scheme 2). That19arises from a charge‐induced [3s, 3s] sigmatropic rearrangement of12– and20from two consecutive [3s, 3s]‐sigmatropic transformations – follows from the reaction of N‐crotyl‐2‐methylaniline (13) in the presence of zinc chloride at 140°. 2‐(1′‐Methylallyl)‐6‐methylaniline (22) and 4‐crotyl‐2‐methylaniline (23) are formed exclusively. Small amounts of 2,3,7‐trimethyl‐indoline (24) and 2‐(cis‐ andtrans‐1′‐methyl‐propenyl)‐6‐methylaniline (cis‐ andtrans‐25) are observed as by‐products. Compound24arises from22in the presence of zinc chloride (scheme 3). Similar results are obtained when N‐allyl and N‐(2′‐methylallyl)‐N‐methyl‐aniline (14and15, respectively) are heated in the presence of zinc chloride. Whereas14gives nearly exclusively 2‐allyl‐N‐methyl‐aniline (28) and only small amounts of the corresponding 1, 2‐dimethyl‐indoline (29) and of 2‐(cis‐andtrans‐propenyl)‐N‐methyl‐aniline (cis‐andtrans‐27),15forms comparable amounts of 2‐(2′‐methylallyl)‐N‐methyl‐aniline (30), 1,2,2‐trimethyl‐indoline (31), and 2‐isobutenyl‐N‐methyl‐aniline (32) (scheme 4). Compound30, and also32, are transformed into31on heating in the presence of zinc chloride.Charge‐induced aromatic amino‐Claisenrearrangements are also observed when N‐allylated anilinium tetraphenylborates are heated at 100–105° in hexamethyl phosphoric acid triamide. Thus, N‐allyl‐ and N‐crotyl‐N, N‐dimethyl‐anilinium tetraphenylborate (16and17, respectively) yield 2‐allyl‐ and 2‐(1′‐methylallyl)‐N,N‐dimethyl‐aniline (33and34, respectively) besides small amounts of N, N‐dimethyl‐aniline. N‐Cinnamyl‐N, N‐dimethyl‐anilinium tetraphenylborate (18) gives, besides appreci

ISSN:0018-019X    

DOI:10.1002/hlca.19730560105

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe mass spectral behaviour of tetraacetyl spermine (2) has been investigated. The fragmentation reactions are characterized by the neighbouring group participation of the amide nitrogen atoms. Only a few reactions can be explained by usual pathways (α‐cleavage, onium reactions). Most of the fragment‐ions are formed by neighbouring group participation:1[M‐COCH3]+‐Ion.2Breakdown of one of the two 1,3‐diaminopropan moieties:m/e242, 256, 268. This type of fragmentation is characteristic for all acetylated 1,3‐diaminopropan‐derivatives e.g. triacetylspermidine.3Expulsion of a neutral amine:m/e169.4SNi‐type reactions, by which cyclic ions a

ISSN:0018-019X    

DOI:10.1002/hlca.19730560106

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractIn addition to the preliminary communication [1] a detailed description of the first partial synthesis of steroidal alkaloid batrochotoxinin A (1) is presented.

ISSN:0018-019X    

DOI:10.1002/hlca.19730560107

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThio‐ and dithio‐carbazic acid alkyl esters, acylated in position 3 by radicals of carboxylic, sulfonic, phosphoric, thiophosphoric or thiophosphonic acids, undergo spontaneous ring closure with phosgene, in absence of any acid binding agent, to form the corresponding 3‐acyl‐5‐alkoxy‐ and ‐5‐alkylthio‐l,3,4‐thiadiazol‐2(3H)‐ones. Similarly 3‐thiophosphorylated 5‐substituted 1,3,4‐oxadiazol‐2(3H)‐ones can be prepared from carboxylic acid hydrazides acylated by thiophosphoric acid radicals. In the latter case, however, a stoichiometric amount of pyridine is necessary to

ISSN:0018-019X    

DOI:10.1002/hlca.19730560108

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractAn NMR. investigation of the state of formaldehyde in acidic solutions has been carried out. Solutions of DCl/D2O/CD3COOD containing two sources of formaldehyde, i.e. paraformaldehyde (I) and trioxane (II), were used for this purpose. In systems I and II the effect of various D2O/CD3COOD ratios, at a constant DCl concentration, was studied, while for II the effect of changing DCl concentration was also investigated. The results show that in aqueous solution, formaldehyde exists primarily as the monomeric and linear oligomeric forms of methylene glycol. Reducing the amount of D2O (at constant DCl concentration), while increasing the CD3COOD content, results in an increase in the polymeric species and in trioxane. In addition, substitution of water by acetic acid results in systems that are catalytically more active than aqueous solutions of the same hydrochloric acid concentration. Along with the usual polymer‐monomer equilibria which exist in such solutions, side reactions of methylene glycol with the hydrochloric acid present also occur to a small extent, e.g. acetylation, substitution of OH by Cl and theCannizzaroreaction. It is suggested that these findings will result in a better understanding of the formaldehyde crosslinking reactions in cotton cellulos

ISSN:0018-019X    

DOI:10.1002/hlca.19730560109

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe polarographic reduction potentials of a series of aromatic sulfones and homologous alkyl tosylates in anhydrous NN‐dimethylformamide have been measured. The relation between reduction potential and structure is discussed on the basis of HMO. calculations, under the assumption that compounds PhSO2X (X = NR1R2, OR, halogens) are sulfone derivatives A critical approach is made of the use of theTaft‐Hammettrelation for correlating half‐wave potentials. The different reduction mechanisms at the electrode observed in aprotic and protic media for the above compounds are satisfactorily accounted for by simple MO. calcula

ISSN:0018-019X    

DOI:10.1002/hlca.19730560110

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe mass spectra of C‐methyl‐inositols and of two of their deuterium‐labelled analogues have been studied. The results indicate that each stereoisomer can be characterized by its mass spectrum. A fragmentation scheme based upon high‐resolution measurements, metastable peaks and deuterium‐labelling is

ISSN:0018-019X    

DOI:10.1002/hlca.19730560111

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY