Structural studies of organoboron compounds. XLIII. 4-[(1-Hydroxycyclohexyl)methyl]-2,2,5-triphenyl-1,3-dioxa-4-azonia-2-borata-4-cyclopentene

Rettig³

et al. 1996

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Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 60%

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Structural studies of organoboron compounds LXIV. Boron chelate formation with glycolohydroxamic acids, and the crystal and molecular structure of 5-(1-hydroxycyclohexyl)-2,2-diphenyl-1,3-dioxa-4-azonia-2-borata-4-cyclopentane

Kliegel¹,

Rettig³

et al. 1996

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“…A possible intermediate 2 could form the cyclic ether 4 by intramolecular condensation and still feature the five-membered BF2 hydroxamate chelate, similar to the cyclic ether compound 8 with an identical difluoroboron chelate ring portion within the molecule (3). Another intramolecular condensation reaction of 1 in the presence of BF3 could give rise to the difluoroboron chelate 5 with the newly formed 2-oxazoline N-oxide moiety as one of the chelating ligands.…”

Section: Introductionmentioning

confidence: 99%

Structural studies of organoboron compounds. XLV. 5,5-Difluoro-2,2-pentamethylene-7,7-diphenyl-1,4,6-trioxa-3a-azonia-5-borata-2,3,4,5,6,7-hexahydroindene

Kliegel¹,

Rettig³

et al. 1991

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. Can. J. Chem. 69, 681 (1991).The reaction of N,2-dihydroxy-N-(1 -hydroxycyclohexyl)methyl-2,2-diphenylacetamide with dimethyl ether-boron trifluoride gives 5,5-difluoro-2,2-pentamethylene-7,7-diphenyl-,4,6-trioxa-3a-azonia-5-borata-2,3,4,5,6,7-hexahydroindene in nearly quantitative yield. Crystals of the product are triclinic, a = 9.4555(5), b = 9.9813(6), c = 10.5139(9) A, a = 72.654(7), P = 77.140(5), y = 88.542(6)", Z = 2, space group p i . The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.044 and R,,. = 0.060 for 2971 reflections with I 2 3u(I). The molecule has a six-membered difluoroboron chelate structure, confirming that the regioselective alkylation of N-substituted hydroxamic acids under non-basic conditions leads to imidate N-oxides in cases where intramolecular alkylation occurs. Bond lengths (corrected for libration): (3) Mots clis : compos&s organoborks, structure cristalline, compost bore.[Traduit par la redaction] Introduction The reaction of the bis(hydroxyalky1) substituted hydroxamic acid 1 with boron trifluoride did not lead to the difluoroboron chelate 2 having the "normal" BF2 hydroxamate structure that usually results from reactions of N-alkylhydroxamic acids with boron trifluoride (I), and which has been established by an X-ray crystallographic study of the simple prototype 3 (2). The crystalline compound obtained from the reaction of 1 with BF3-0Me2 produced spectra and elemental analyses showing not only HF elimination but also loss of H20. Neither infrared bands for 0-H stretching vibrations nor OH-proton signals in the 'H nmr spectra, both of which would arise from the hydroxyl groups of 2, were observed. These data suggest an intra-or intermolecular condensation of 1 and difluoroboron chelate formation leading to structures such as 4-7.A possible intermediate 2 could form the cyclic ether 4 by intramolecular condensation and still feature the five-membered BF2 hydroxamate chelate, similar to the cyclic ether compound

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“…Alternative isomeric structures include an open-chain adduct 5 of diphenylborinic acid at a 2 -o x a~o l~n e N-ox~de moiety, formed by cyclocondensation during the reactlon with the Lewis-acid boron compound. The postulated isomer 5, however, was ruled out by an X-ray crystallographic analysis (1).…”

Section: Introductionmentioning

confidence: 99%

Structural studies of organoboron compounds. XLVI.¹ 5,5-Pentamethylene-2-phenyl-4,5-dihydrooxazol-N-oxide(NOB)trifluoroborane

Kliegel¹,

Rettig³

et al. 1991

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