摘要:

The stereochemistry of the hydroborations of 4-tert-butyl-2,2-dimethyl-l-methylenecyclohexane and of 3,3,5-trimethyl-1-methylenecyclohexane has been studied for comparison with that of the hydroboration of 4-tert-butyl-1-methylenecyclohexane which also was examined.cis- andtrans-4-tert-butyl-1-hydroxyrnethyl-2,2-dimethylcyclohexane as well ascis- andtrans-1-hydroxymethyl-3,3,5-trimethylcyclohexane were obtained in a pure state and their configurations proved by means of the corresponding acids and esters. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v75-283

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The Δ4-3-ketosteroid analog (± )-4a-methyl-4,4a,5,6,7,8-hexahydro-2(3H) naphthalenone (1) is hydroxylated at both C-8α and C-8β byRhizopusarrhizusATCC 11145. The ratio of C-8α to C-8β hydroxylation is compared with that obtained from the peracid oxidation of 2-ethoxy-4a-methyl-3,4,4a,5,6,7-hexahydronaphthalene (4) and a mechanism is proposed for both microbial and chemical hydroxylation in which the stereochemistry of the product is transition state controlled. The significance of this to the mechanism of microbial C-6β hydroxylation of Δ4-3-ketosteroids is discussed.

ISSN:0008-4042    

DOI:10.1139/v75-284

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Condensation ofo-hydroxybenzyl alcohol (4) with 1,3-cyclohexanedione (7) in hexamethylphosphoramide gives 3,4-dihydro-l(2H)-xantnenone (9). Treatment of the tosylhydrazone of9with methyllithium gives 3,4-dihydroxanthene (12), which undergoes Diels–Alder reactions with dimethyl acetylenedicarboxylate and propiolonitrile to give the bridged xanthenes15and17, respectively. Condensation ofo-hydroxybenzyl alcohol (4) with 4-carboxamido-1,3-cyclohexanedione (29) and 4-carbomethoxy-1,3-cyclohexanedione (38) gives 2-carboxamido-(30) and 2-carbomethoxy-3,4-dihydro-l(2H)-xanthenone (39), respectively.

ISSN:0008-4042    

DOI:10.1139/v75-285

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Oxidation of mesitol (8) with lead tetraacetate in acrylic acid followed by gentle heating gives 6-hydroxy-4,6,7-trimethyl-5-oxobicyclo[2.2.2]oct-7-ene-2-carboxylic acid lactone (13), which is considered to be formed via intramolecular cycloaddition of 6-acryloxy-2,4,6-trimethyl-2,4-cyclohexadienone (11). Similar treatment of 4-methylxanthen-3-o1 (7) gives the corresponding bridged xanthene keto lactone 5. Ketalization of this with ethylene glycol, followed by treatment with methylmagnesium iodide, hydrolysis, and pyrolysis gives the bridged xanthene keto ether4, which possesses many of the structural features of the nucleus of the naturally occurring coloring matters morellin and gambogic acid.

ISSN:0008-4042    

DOI:10.1139/v75-286

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The structure of ferric phosphate at room temperature was refined on a Dauphiné-twinned crystal using full-matrix least-squares methods. The finalRvalue was 0.078 for 487 symmetry-independent reflections whose intensities were corrected for twinning. The structure was found to be isotypic with AlPO4(berlinite) with the space groupP3121 and four formula units in a unit cell defined bya = 5.036(2) andc = 11.255(4) Å. The structure is also closely related to that of α-quartz with a nearly doubled c-axis because of the ordering of Fe and P atoms. The PO4tetrahedron is almost regular with a mean P—O distance of 1.526 Å. The Fe3+ion is tetrahedrally coordinated with an average Fe—O distance of 1.853 Å.

ISSN:0008-4042    

DOI:10.1139/v75-287

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The photochemistry of thetrans-1,3,5-hexatriene-p-benzoquinone Diels–Alder adduct has been investigated. Irradiation of this material in its long wavelength n → π* absorption band leads to a single photoproduct in high yield. A single crystal X-ray structure determination shows this product to be tetracyclo[6.4.0.02,11.04,9]dodec-6-ene-3,10-dione, the result of a novel regiospecific intramolecular 2 + 2 photoaddition between the side chain vinyl group and the enedione double bond. Crystals of tetracyclo[6.4.0.02,11.04,9]dodec-6-ene-3,10-dione are monoclinic,a = 7.5290(7),b = 19.072(1),c = 6.7237(4) Å, β = 107.918(6) °,Z = 4, space groupP21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a finalRof 0.041 for 1603 reflections withI ≥ 3σ(I). The structure consists of well-separated molecular units. Bond distances are: C=O, 1.216 and 1.219(2), C=C, 1.318(2), mean C(sp3)—C(sp2), 1.508, mean C(sp3)—C(sp3), 1.560 in the four-membered ring and 1.544 elsewhere, mean C(sp3)—H, 0.99, and mean C(sp2)—H, 0.95 Å. Bond distances between nonhy drogen atoms have been corrected for thermal motion. A possible rationalization for the observed photoprocess is discussed in terms of conformational and radical stability effects.

ISSN:0008-4042    

DOI:10.1139/v75-288

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Metastable ion peaks for the fragmentation C2H4O+ • → C2H3O+ + H•have been studied in the first field-free region of a double focussing mass spectrometer under conditions of good energy resolution. Three isomeric C2H4O+ •ions were generated(b) CH3CHO+, and (c) CH2=CHOH+ •from ethylene oxide, acetaldehyde, and ethyl vinyl ether respectively, each fragment producing a different1m* peak having a characteristic shape and kinetic energy release. The above ions do not therefore interconvert prior to fragmentation and their characteristic1m* peaks permit their unequivocal identification, thus providing a powerful method for ion structure determination.In agreement with some recent collisional activation data it was found that the unbranched aldehydes, cyclic alcohols, and 2-haloethanols investigated generated (c) type C2H4O+ •ions. These are also produced by glycidol and α-furfuryl alcohol. Some compounds generated composite1m* peaks,e.g. 1,3-dioxolane produces (a) and (c) ions, while compounds which produce prominent C2H5O+ions having the protonated acetaldehyde structure, generatem/e44 ions of structures (b) and (c). In isopropanol these components were separated by a deuterium labelling experiment. Contrary to earlier proposals, pyruvic acid does not generate (b) type ions but produces predominantly ions of structure (c).

ISSN:0008-4042    

DOI:10.1139/v75-289

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The structure of 2-(4′-carbomethoxy-2′-nitrophenoxy)-1,3,5-trimethylbenzene, C17H17NO5, has been determined by X-ray diffraction. The crystals are monoclinic,a = 8.352(4),b = 17.892(10),c = 10.966(6) Å, β = 100.59(3) °,P21/cwithZ = 4. The intensities of 3877 independent reflections were measured on a four circle diffractometer; 2272 of these reflections were used to obtain a final least-squares residual of 0.053 and traditionalRfactor of 0.054. The general conformation is similar to that found earlier for differently substituted diphenyl ethers. Comparison of this structure with those previously determined indicates that distortions in ring angles are primarily a result of electronic rather than steric effects.

ISSN:0008-4042    

DOI:10.1139/v75-290

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The crystal structure of 2-(2′,6′-dinitrophenoxy)-t-butylbenzene, C16HI5N2O5, has been determined by X-ray diffraction. The crystals are monoclinic, space groupP21/c:a = 13.949(9),b = 9.652(6),c = 23.806(12) Å, β = 93.82(5),Z = 8. The integrated intensities of 6811 reflections were recorded with a four circle automated diffractometer at 20 °C; 3334 of these reflections were used in the refinement of the structure to a least-squares weighted residual of 0.057 and a traditionalRfactor of 0.057.The two crystallographically independent molecules both have the skew-t-butyl-distalconformation, suggesting that the steric effects of the twoortho-nitro groups play a greater role in determining the conformation than does conjugation with the bridging oxygen atom.

ISSN:0008-4042    

DOI:10.1139/v75-291

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The structure of 2-(4′-carbomethoxy-2′-nitrothiophenyl)-1,3,5-trimethylbenzene, C17H17-NO4S, has been determined by X-ray diffraction. The crystals are monoclinic,a = 18.616(15),b = 5.739(8),c = 15.712(14) Å, β = 101.97(3)°,P21/cwithZ = 4. The intensities of 3820 independent reflections were measured on a four circle diffractometer; 2825 reflections were used in the refinement of the structure to give a final least-squares weighted residual of 0.059 and a traditionalRfactor of 0.054. The presence of electron-withdrawing groups on one of the phenyl rings increases the conjugation between the ring and the sulfur atom in a similar manner as that observed in diphenyl ethers. The mesityl ring is nearly orthogonal to the C—S—C plane.

ISSN:0008-4042    

DOI:10.1139/v75-292

出版商:NRC Research Press    

年代:1975

数据来源: NRC