摘要:

This paper reports a retrosynthetic analysis that led to the conception of a synthetic strategy for the construction of ryanodol (2). The preparation of a key diene, i.e., spirolactone dienone47(19 → 31 → 33 → 48 → 49 → 52 → 47), and its Diels–Alder reaction with methyl vinyl ketone are reported.Keywords: strategy, synthesis, ryanodol, diterpene.

ISSN:0008-4042    

DOI:10.1139/v90-021

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper reports several model studies that were necessary for the rational conception of a simple four-step synthesis (6 + (S)-74 → 81a–b → 83  87 → 89) (Scheme 11) of the carbonate derivative89of the optically active pentacyclic dihydroxy ketoaldehyde87, an important key intermediate for the synthesis of (+)-ryanodol (5). The optically active vinyl ketone (S)-74that was used as starting material was prepared in four steps fromd-carvone ((S)-94) (Scheme 13). The preparation of the other starting material, theo-spirolactone dienone6, was reported in Part I.Keywords: strategy, synthesis, ryanodol, key intermediate, diterpene.

ISSN:0008-4042    

DOI:10.1139/v90-022

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper reports several studies that were carried out to learn how to transform the dextrorotatory pentacyclic key intermediate5into (+)-anhydroryanodol (6). This transformation requires 24 steps, and takes place via the following intermediates:5 → 11 → 19 → 34 → 36 → 39 → 144 → 150 → 6. The preparation of the key pentacyclic intermediate5is reported in Parts I and II of this series.Keywords: anhydroryanodol, ryanodol, diterpene, organic synthesis, strategy.

ISSN:0008-4042    

DOI:10.1139/v90-023

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper reports the transformation of (+)-anhydroryanodol (6) to (+)-ryanodol (7) by reductive cyclization of lactone epoxide derivatives9and20(Scheme 4).Keywords: anhydroryanodol, ryanodol, diterpene, synthesis, reductive cyclization.

ISSN:0008-4042    

DOI:10.1139/v90-024

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Crystals of 7-azaindole (,a = 11.312(4),b = 14.960(6),c = 15.509(5) Å, α = 102.86(3), β = 108.78(3), γ = 90.71(3)°,Z = 16,R = 0.052) contain tetrameric units of approximateS4symmetry, in which the molecules are associated by means of four complementary N—H … N hydrogen bonds. [CH3Hg(7-azaindole)]NO3(,a = 7.818(3),b = 7.884(3),c = 9.135(4) Å, α = 97.89(3), β = 109.13(3), γ = 103.28(3)°,Z = 2,R = 0.039) contains well-separated nitrate ions and complex cations in which the methylmercury group is linearly bonded to the pyridine nitrogen atom, whereas the five-membered ring remains protonated. In the neutral [CH3Hg(azaindolate)] complex (,a = 10.926(10),b = 11.333(8),c = 11.647(10) Å, α = 92.13(8), β = 104.83(9), γ = 111.86(7)°,Z = 6,R = 0.048), methylmercury groups have substituted the N—H proton in the five-membered ring for the three symmetry-independent molecules. Intermolecular secondary Hg … N bonds are found with pyridine nitrogens.Keywords: azaindole, methylmercury, crystal structure.

ISSN:0008-4042    

DOI:10.1139/v90-025

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Heterojunctions of the type CdS/chloroaluminum phthalocyanine have been obtained by using the following methods to prepare the CdS layer: electrochemical deposition in dimethylsulfoxide (I); electrochemical aqueous deposition at constant reduction potential (II), or cyclic potential (III), or constant oxidation current (IV); and chemical aqueous deposition (V). The CdS films were characterized by SEM, EDAX, optical microscopy with Nomarski interference, X-ray diffraction, and photoelectrochemistry in polysulfide solution. The best cells show a conversion efficiency of about 0.2% under white light illumination of 90 mW cm−2. They were obtained with a 1.0 μm thick layer of the organic semiconductor and a 0.4 μm thick CdS film prepared by method I. This method yields a polycrystalline electrode characterized by large plates (1–3 μm) of tightly packed single oriented (111) cubic CdS crystallites showing low sub-bandgap absorption. The better performances of the CdS/ClAlPc heterojunctions obtained by method I can be understood in terms of absorbance of the CdS layer of optimum thickness, hole diffusion length in the CdS and electron–hole recombination efficiency at the CdS/ClAlPc interface.Keywords: CdS, phthalocyanine, heterojunction, organic semiconductor, photovoltaic cell.

ISSN:0008-4042    

DOI:10.1139/v90-026

出版商:NRC Research Press    

年代:1990

数据来源: NRC