摘要:

AbstractTetramethylene‐4,4′‐bis(1‐arylthiosemicarbazides) were converted into tetramethylene‐3,3′‐bis(4‐aryl‐5‐mercapto‐1,2,4‐triazoles) and tetramethylene‐2,2′‐bis[5‐(arylamino)‐1,3,4‐thiadiazoles] under different reaction conditions. The bis(5‐mercapto‐1,2,4‐triazoles) were converted into their thiolates on treatment with alkyl halides. Some com

ISSN:0165-0513    

DOI:10.1002/recl.19770960702

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractOn treatment with liquid ammonia at −33° the quaternary pyrimidinium saltsi.e.4‐ethoxy‐1‐ethyl‐ (1) and 4,6‐diethoxy‐1‐ethyl‐pyrimidinium tetrafluoroborate (3) undergo amino‐de‐ethoxylation, yielding 1,4‐dihydro‐1‐ethyl‐4‐imino‐pyrimidine hydrogen tetrafluoroborate (7) and a mixture of 1,4‐dihydro‐6‐ethoxy‐1‐ethyl‐4‐imino‐ (9) and 1,6‐dihydro‐4‐ethoxy‐1‐ethyl‐6‐imino‐pyrimidine hydrogen tetrafluoroborate (11), respectively.1HNMR and13CNMR spectroscopic evidence is presented for the fact that compounds 1 and 3 easily give σ‐adducts at position 2. Using15N‐labelled ammonia it was shown that in these amino‐de‐ethoxylation reactions the substitution at C(4) or C(6) does not involve ring opening but probably occursviaan SN(AEn) process. Reaction of 4‐ethoxy‐1‐ethyl‐2‐phenyl‐ (2), 6‐ethoxy‐1‐ethyl‐4‐phenyl‐ (4), 4,6‐dimethoxy‐1‐ethyl‐2‐phenyl‐ (5) and 4,6‐dimethoxy‐1‐ethyl‐2‐methyl‐pyrimidinium tetrafluoroborate (6) with liquid ammonia gives besides the amino‐de‐ethoxylation product degenerate ring transformations leading to theN‐de‐ethylated products14–16and 4(6)‐(ethylamino)pyrimidines17‐19. The salt11and 1,6‐dihydro‐1‐ethyl‐6‐

ISSN:0165-0513    

DOI:10.1002/recl.19770960703

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractThe crystal and molecular structures of two isomeric compounds, 4,6‐diethoxy‐1‐ethylpyrimidinium tetrafluoroborate and 6‐ethoxy‐1,3‐diethyl‐1,4(3,4)‐dihydro‐4‐oxopyrimidinium tetrafluoroborate, reaction products of 4,6‐diethoxypyrimidine with Meerwein reagent [O(C2H5)+3BF−4], have been determined by means of X‐ray diffraction.4,6‐Diethoxy‐1‐ethylpyrimidinium tetrafluoroborate is monoclinica= 10.794,b= 13.361,c= 10.892 Å, β = 112.6°, space groupP21/n, four molecules per unit cell.6‐Ethoxy‐1,3‐diethyl‐1,4(3,4)‐dihydro‐4‐oxopyrimidinium tetrafluoroborate is monoclinic,a= 17.637,b= 14.054,c= 11.501 Å, β = 101.7°, space groupC2/c, eight molecules per unit cell.In both structures the fluoroborate ions are disordered. The bond distances in the π‐electron systems are reasonably well descri

ISSN:0165-0513    

DOI:10.1002/recl.19770960704

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

Abstract(‐)‐(S)‐2‐Chloro‐3‐(5‐imidazolyl)propanol (4) was synthesized by reduction of both the acid chloride and the methyl ester of (‐)‐(S)‐2‐chloro‐3‐(5‐imidazolyl)propionic acid. The optical rotatory dispersion and circular dich

ISSN:0165-0513    

DOI:10.1002/recl.19770960705

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractA new stereospecific synthesis for substituted 1‐alkenyl sulfides, phosphines and tin compounds RR′C=CHX (X = −SMe, −PPh2, −SnPh3) is presented, starting from stereospecifically generated vinylcuprates [RR′C=CHCu(Br, I or R)]MgX′ (X′ = Cl or Br) and MeSSO2Me, Cl−PPh2and Cl−SnPPh3, respectively, using tetrahydrofuran as solvent.Iodovinylcuprates [RR′CCHCu−I]MgX′ are obtained by selective methylation of the R‐radical in the mixed homocuprates [RR′CCHCu−R]MgX

ISSN:0165-0513    

DOI:10.1002/recl.19770960706

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractThe sulfines1–9in which theo‐positions of the aryl ring A are substituted by methyl groups, have a high rotational barrier about the aryl A to sulfine bond (bond α). Due to this α‐barrier, sulfines1and2exist as a pair of rotational enantiomers (atropisomerism). The symmetrically substituted sulfines3,4,7,8and9possess a prochiral centre,viz. the mesityl‐CSO part, provided rotation about bond α is restricted. With rapid rotation about bond α this prochirality disappears (thermally labile prochirality). Chiral lanthanide shift reagents are employed to uncover these chiral properties. The atropisomerism in the sulfines1and2and the thermally labile prochirality in the sulfines3,4, 7, 8and9are demonstrated by use of chiral shift reagent. Moreover, chiral shift reagents are successfully used to determine the α‐barrier in the su

ISSN:0165-0513    

DOI:10.1002/recl.19770960707

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

Abstract“Epimestranol” (6) has been prepared from the 16α,17‐epoxide5by reduction with LiAlH4. The structures of several by‐products have been elucidated and a mechanism for their formation is discussed. Both “mestranol” (3) and “epimestranol” failed to formp‐tosylates and only “mestranol” could be converted into thep‐toluenesulfinate which readily rearranged to the allenic sulfone14. “Epimestranol” was transformed into a mixture of the two epimeric 17‐sulfone

ISSN:0165-0513    

DOI:10.1002/recl.19770960708

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractMINDO/3 and STO‐3G MO calculations including geometry optimization have been performed for nonlinear C6H+5structures. The phenyl cation5is the lowest energy compound on the surface, followed by the nonclassical pyramidal carbenic structure4. Other local minima include the bicyclic carbene6and the benzvalenyl cation7. Fairly good agreement between the results from both methods was obtained. The electronic structure of4is explained using orbital interaction diagrams which show the stabilization of the cyclopentadienyl cation by the apical carbon atom and the relation between4and pyramidal transition‐metal complexes. The electronic structure of6is related to that of the bicyclo[3.1.0]hexenyl cation12. Activation energies for rearrangement reactions on the energy surface show that4can probably be studied starting from benzvalene‐type precu

ISSN:0165-0513    

DOI:10.1002/recl.19770960709

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19770960710

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractReduction of trifluoroacetophenone by solid‐supported NADH models has been demonstrated and shown to be dependent upon the length of the spacer unit between the polymer surface and the reagen

ISSN:0165-0513    

DOI:10.1002/recl.19770960711

出版商:WILEY‐VCH Verlag    

年代:1977

数据来源: WILEY