摘要:

AbstractA convenient synthesis is described of (±)‐5‐hydroxymarmesin, 4‐hydroxy‐2‐(1‐hydroxy‐1‐methylethyl)‐2,3‐dihydro‐7H‐furo[3,2‐g][1]benzopyran‐7‐one, a physiological intermediate in the biogenetic pathway of 5‐O‐alkylfurocoumarins. The synthesis was achieved by a regiospecific 6‐C isoprenylation of 5,7‐diacetoxy‐coumarin; the 6‐C isoprenylated derivative is then submitted to an oxidative cyclization obtaining mainly the title

ISSN:0022-152X    

DOI:10.1002/jhet.5570180301

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractReaction of 2‐bromo‐1‐phenylethanones with diethanolamine gave 2‐hydroxymorpholines. Acetylation gave mono or diacetates. Acid catalyzed dehydrations gave several types of products whose structures are di

ISSN:0022-152X    

DOI:10.1002/jhet.5570180302

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractThe ability of 2‐amino‐4‐hydroxy‐7H‐pyrimido[4,5‐b][1,4]oxazine derivatives to inhibit dihydrofolate reductase led to a search for means of synthesizing new side chain substituted analogs of this marginally stable pyrimidooxazine system. A study of the synthesis and use of 6‐functionalized pyrimido[4,5‐b][1,4]oxazines for coupling side chains was begun and has now revealed methods for couplingp‐aminobenzoic acid with 2‐amino‐4‐hydroxy‐6‐carboxy‐7H‐pyrimido[4,5‐b][1,4]oxazine and hydrolyzed 2‐amino‐4‐hydroxy‐6‐carbe‐thoxymethylene‐6,7‐dihdyro‐5H‐pyrimido[4,5‐b][1,4]oxazine. The products

ISSN:0022-152X    

DOI:10.1002/jhet.5570180303

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractReactivity towards alkylating agents in relation to the capacity to bind sodium ions of 1,2,6‐thiadiazine 1,1‐dioxide derivatives is described. The compounds studied are:1, 4‐nitro‐,2, 4‐cyano‐,3,4‐ethoxycarbonyl‐2H,6H‐1,2,6‐thiadiazin‐3‐one 1,1‐dioxide and4, 3‐amino‐4‐cyano‐6H‐1,2,6‐thiadiazine 1,1‐dioxide. Methylation with dimethyl sulfate of 4‐nitro‐ and 4‐cyanothiadiazines1and2, which show the capacity to bind sodium ions, takes place regioselectively at position 2, whilst the thiadiazines which lack this feature (3and4) are methylated at 2 and 6, and 6 respectively. On using diazomethane, in the absence of alkaline ions, no selectivity was observed. Glycosidation reactions of1, 3and4have also been carried out. The structure of the newly synthesized compounds are discussed on the bas

ISSN:0022-152X    

DOI:10.1002/jhet.5570180304

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractThe structures of four macrocyclic polyether sulfides have been determined by single crystal x‐ray diffraction methods. The compounds studied were 1,4,7‐trithia‐12‐crown‐4, 1,4‐dithia‐15‐crown‐5, 1,4‐dithia‐18‐crown‐6 and 1,10‐dithia‐18‐crown‐6. In all four compounds the potential donor sulfur atoms point out of the ring. This causes t

ISSN:0022-152X    

DOI:10.1002/jhet.5570180305

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractThe single crystal X‐ray diffraction structure of 2‐(2′‐pyridylthio)‐3‐nitropyridine is reported. A non‐bonded interaction was observed between the sulfur atom and one of the oxygen atoms of the nitro group with an interatomic distance of 2.678 A. Examination of the molecule's behavior in solution by13C‐nmr spin‐lattice (T1) relaxation measurements showed the non‐nitro bearing pyridyl ring to reorient anisotropically about the C2′‐C5′ bond axis. In contrast, the nitro substituted pyridine ring did not appear to exhibit anisotropic reorientation about the corresponding C2‐C5 bond axis. Rather, approximately equivalent relaxation times were noted for all protonated ring carbons, indicating that the relaxations of this portion of the molecule were governed by the overall isotropic reorientation of the system. Based on these observations, it was concluded that the intramolecular sulfur‐nitro interaction also operates in the solution state and is sufficiently strong to prevent free rotation of the substituted portion of the mole

ISSN:0022-152X    

DOI:10.1002/jhet.5570180306

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractThe title compounds (4a,b) were synthesized starting with dimethylα,α'‐dibromo‐o‐benzenediacetate andt‐butyl carbazate. Alternate approaches to 4 involving reduction of the appropriate 2‐nitrosoisoindoline were found unsuitable because of predominant sid

ISSN:0022-152X    

DOI:10.1002/jhet.5570180307

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractThe synthesis of the 3‐azaphenoxathiin ring system and its molecular structure are reported. Based on13C‐nmr chemical shift additivities associated with the insertion of an annular nitrogen atom and the observed13C‐nmr shift of Cα, the title compound was predicted to have a dihedral angle θ = 160.2°. The observed dihedral angle from the crystal structure was found to be θ = 167.07° which is in reasonably good agreement with the predicted value. It is proposed that the position of the annular nitrogen atom is solely in‐control of the observed di

ISSN:0022-152X    

DOI:10.1002/jhet.5570180308

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

Abstractcis‐2‐Aryl‐3‐isopropenyl‐1,3‐dimethylpyrrolidines Ha and IIb have been synthesized by an unambiguous way, thus confirming the structure of the methylene derivatives obtained as by‐products in the Stevens rearrangement of 1‐benzyl‐1,3,4‐trimethyl‐1,2,5,6‐tetrahydropyridinium salts Ia and Ib. The synthesis is based on the acid‐induced intramolecular cyclization between an iminium salt and the α‐position of a ketal group. Thus, condensation between amino ketal XXI, preparedviaGabriel synthesis from 5‐chloro‐3‐methyl‐2‐pentanone, and the appropriate aldehyde afforded imines XXI. Their treatment with dry hydrogen chloride followed by acid hydrolysis and methylation gave 3‐acetylpyrrolidines IV, which were transformed into the isopropenyl derivatives II by reaction wit

ISSN:0022-152X    

DOI:10.1002/jhet.5570180309

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY

摘要:

AbstractN,N'‐Dimethylthiourea and 3,4,5,6‐tetrahydro‐2‐pyrimidinethiol were allowed to react with 2‐chloro‐nicotinonitrile (1) and their products investigated by standard methods and by carbon‐13 nmr. In both instances, displacement of the chlorine occurred by nitrogen not the sulfur of the thioureas. Secondary cyclizations occurred by attack of nitrogen on the nitrile to furnish3a, and by sulfur on the nitrile to give4b, a new ring system. Tricyclic4bwas hydrolyzed in dilute acid to give5, or alkylated with methyl iodide in the presence of sodium hydride to give the ring op

ISSN:0022-152X    

DOI:10.1002/jhet.5570180310

出版商:Wiley‐Blackwell    

年代:1981

数据来源: WILEY