摘要:

AbstractA series of novel phosphonodipeptides has been synthesized from diphenyl α‐aminoalkylphosphonates and N‐chloroacetyl‐N‐alkyl (or aryl)glycine ethyl esters. The structures of all the compounds prepared were proved by1H NMR, IR, MS, and elemental analyses. The bioassay tests showed that some of the compound have good herbicidal

ISSN:1042-7163    

DOI:10.1002/hc.520040102

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe spirophosphorane 4 underwent reaction with a series of benzene‐sulphenic esters3to give the corresponding isolable alkoxyphosphoranes. The reactivities of benzenesulphenic esters3in this reaction were seen to be dependent on steric hindrance of the R groups. The yields of alkoxyphosphoranes were influenced by the reaction temperature. The probable mechanism was suggested in terms of experimental observation

ISSN:1042-7163    

DOI:10.1002/hc.520040103

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSix O, O‐diethyl‐N‐acylphosphoramidates (1a‐f) were synthesized. The reactions of their conjugate bases with haloalkanes were studied. The N/(phosphoryl)O/(carbonyl)O regioselectivity varied greatly, depending on the substrate, the haloalkane, the base, and other reaction conditions. The earlier [17] reaction of N‐formyl substrate1athat led to the N‐phosphorylated formamidine was extended to other substrates1. Again, the yields and the selectivity depended strongly on the structure of

ISSN:1042-7163    

DOI:10.1002/hc.520040104

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractExamination of several model organophosphorus compounds, bicyclic phosphates (1), p‐substituted phenylphosphonates (2), and acidic alkylphosphonates (3) reveals that the polar substituent effect in organophosphorus esters parallels that of carbon compounds. No significant variation in polar effects of different alkyl groups with up to 10 carbon atoms is observed. As demonstrated by us, the commonly used Kabachnik polar constant σΦfor alkyl groups of organophosphorus compounds reflects the steric effect associated with steric hindrance to solvation of acidic anions. Therefore, a set of solvation steric parameters Epshas been calculated from pKavalues of organophosphorus acids. This parameter can be applied to describe the structural effect on dissociation of organic acids and, after suitable modification, may reflect the steric effect of alkyl groups in hydrolytic reactions of organophosphorus est

ISSN:1042-7163    

DOI:10.1002/hc.520040105

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA brief synthesis of endo‐2‐bromo‐5‐thiabicyclo [2.1.1]hexane (9) has been developed involving conversion of 3‐cyclopentenol (6) to 3‐thioacetoxycyclopentene (7), bromination of this giving trans‐1,2‐dibromo‐4‐thioacetoxycyclopentane (8), and treatment of the latter with base. Compound9is oxidized to its S‐oxide10and S, S‐dioxide11. Comparative13C and1H NMR

ISSN:1042-7163    

DOI:10.1002/hc.520040106

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractPyrromethene–BF2complexes (P–BF2)7were obtained from α‐unsubstituted pyrroles5by acylation and condensation to give intermediate pyrromethene hydrohalides6followed by treatment with boron trifluoride etherate. Conversion of ethyl α‐pyrrolecarboxylates4to α‐unsubstituted pyrroles5was brought about by thermolysis in phosphoric acid at 160°C, or by saponification followed by decarboxylation in ethanolamine at 180°C, or as unisolated intermediates in the conversion of esters4to pyrromethene hydrobromides6by heating in a mixture of formic and hydrobromic acids. Addition of hydrogen cyanide followed by dehydrogenation by treatment with bromine converted 3,5,3′,5′‐tetramethyl‐4,4′‐diethylpyrromethene hydrobromide9to 3,5,‐3′,5′‐tetramethyl‐4,4′‐diethyl‐6‐cyanopyrromethene hydrobromide6bb, confirmed by the further conversion to 1,3,5,7‐tetramethyl‐2,6‐diethyl‐8‐cyanopyrromethene–BF2complex7bbon treatment with boron trifluoride etherate.An alternation effect in the relative efficiency (RE) of laser activity in 1,3,5,7,8‐pentamethyl‐2,6‐di‐n‐alkylpyrromethene–BF2dyes depended on the number of methylene units in the n‐alkyl substituent, ‐(CH2)nH, to give RE ≥ 100 when n = 0,2,4 and RE 65, 85 when n = 1,3. (The RE 100 was arbitrarily assigned to the dye rhodamine 6G). The absence of fluorescence and laser activity in 1,3,5,7‐tetramethyl‐2,6‐diethyl‐8‐isopropylpyrromethene–BF2complex7pand a markedly diminished fluorescence quantum yield (Φ 0.23) and lack of laser activity in 1,3,5,7‐tetramethyl‐2,6‐diethyl‐8‐cyclohexylpyrromethene–BF2complex7qwere attributed to molecular nonplanarity brought about by the steric interference between each of the two bulky 8‐substituents with the 1,7‐dimethyl substituents. An atypically low RE 20 for a peralkylated dye without steric interference was observed for 1,2,6,7‐bistrimethylene‐3,5,8‐trimethylpyrromethene–BF2complex7j. Comparisons with peralkylated dyes revealed a major reduction in RE 0–40 for the six dyes7u–zlacking substitution at the 8‐position.Low laser activity RE was brought about by functional group (polar) substitution in the 2,6‐diphenyl derivative7I, RE 20, and the 2,6‐diacetamido derivative7m, RE 5, of 1,3,5,7,8‐pentamethylpyrromethene–BF2complex (PMP–BF2)7aand in 1,7‐dimethoxy‐2,3,5,6,8‐pentamethylpyrromethene–BF2complex7n, RE 30. Diethyl 1,3,5,7‐tetramethyl‐8‐cyanopyrromethene‐2,6‐dicarboxylate–BF2complex,7aa, and 1,3,5,7‐tetramethyl‐2,6‐diethyl‐8‐cyanopyrromethene–BF2complex,7bb, offered examples of P–BF2dyes with ele

ISSN:1042-7163    

DOI:10.1002/hc.520040107

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

Abstract2,4,6‐Trinitrobenzylamine was synthesized via 2,4,6‐trinitrophenylacetic acid and 2,4,6‐trinitrobenzyl isocyanate. The title compound decomposes at room temperature but forms a stable hydrochloride and acetyl deriv

ISSN:1042-7163    

DOI:10.1002/hc.520040108

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractNovel sulfur‐containing spiro compounds such as 7,11‐diaryl‐9‐thia‐2,4‐diazaspiro [5,5] undecane‐1,3,5‐trione 9,9‐dioxides (2), 6,10‐diaryl‐8‐thia‐2,3‐diazas‐piro[4,5]decane‐1,4‐dione‐8,8‐dioxides (3) and 6,10‐diaryl‐2‐oxo‐8‐thia‐3‐azaspiro [4,5] decane‐1,4‐dione‐8,8‐dioxides (5) have been prepared by the condensation of 4‐dimethoxycarbonyl/diethoxycarbonyl‐3,5‐diaryl‐1‐thiane 1,1‐dioxides (1) with urea, hydrazine hydrate, and hydroxylamine hydrochloride, respectively. The N‐substituted derivatives (4and6) of3and5have also been prepared by acylation and nitrosation. The structures of2, 3, and

ISSN:1042-7163    

DOI:10.1002/hc.520040109

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe double bond of the P‐alkoxy 3,4‐dimethyl‐2,5‐dihydro‐1H‐phosphole 1‐oxides reacts easily with dichlorocarbene to give two diastereomers of an unstable adduct useful in the synthesis of ring expanded products, such as 1,2‐dihydrophosphinine oxides or 1,2,3,6‐tetrahydrophosphinine oxides. The former can be prepared by thermolysis of the adducts, while the latter are obtained by cyclopropane ring opening effected by silver nitrate in an alcoholic solvent. The preparation of the double‐bond isomers of 1‐alkoxy‐tetrahydrophosphinine oxides containing only one methyl substituent in the ring is also described. The reaction of dihydro‐1H‐phosphole oxides with dichlorocarbene can be modified to give P‐alkoxy 1,4‐dihydrophosphinine o

ISSN:1042-7163    

DOI:10.1002/hc.520040110

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe reduction of representative O‐methyl oxime ethers1–4with aluminum hydride in tetrahydrofuran yielded allylic amines and saturated aziridines as the main products. The stereochemical course of the reduction to aziridines depends on the oxime ether configuration. Thus,E–3, E–4andZ–3, Z–4gave15, 16and21, 22, respectively, with high stereoselectivity. Higher reactivity of Z than E isomers was utilized for the preparation of pure E isomers of oxime ethers from E,

ISSN:1042-7163    

DOI:10.1002/hc.520040111

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY