Structural studies of organoboron compounds. XVII. Preparation and crystal and molecular structure of 3a-methyl-2,4,9a-triphenyl-1,2,3a,4,9,9a-hexahydro-1,3,9-trioxa-3a-azonia-2-bora-9a-boratacyclopenta[b]naphthalene

Abstract

Structural studies of organoboron compounds. XVII.' Preparation and crystal and molecular structure of 3a-methyl-2,4,9a-triphenyl-1,2,3a,4,9,9a-hexahydro-1,3,9-trioxa-3a-azonia-2-bora-9a-boratacyclopenta Thc titlc compound was prepared by the reaction of 8-mcthyl-6.6-diphenyI-5,7-dioxa-8-azonia-6-borata-6.7-dihydro-5H-benzocycloheptene (1) with phenylboronic acid. Crystals of 3n-methyl-2.4,9o-triphcnyl-I,2,3n,4,9,9n-hexahydro-1,3,9-trioxa-3a-azonia-2-bora-9a-boratacyclopenta[b]naphthalene are monoclinic. a = 1 I .8548(4), b = 22.7837(4), c = 8.5457 (3) A, P = 106.952(2)", Z = 4, space group P21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.040 and R,,. = 0.047 for 2970 reflections with I 2 3u(I). The molecule was found to bc a formal addition product between 1 and PhBO which had undergone a 1.4-shift of a phenyl group from boron to carbon. The backbone of thc molecule consi:ts of a folded system of three fuscd rings. The structure contains thc longest known B(. On a prtpard le compost mentionnt dans le titre en faisant rdagir de I'acide phtnylboronique avec le mdthyl-8 diphdnyl-6,6 dioxa-5,7 azonia-8 borata-6 dihydro-6.7 5H-benzocyclohept~ne ( I ) . Les cristaux du mkthyl-3a triphtnyl-2,4,9n hexahydro-1 ,2,3a34,9,9n trioxa-1,3,9 a~onia-30 bora-2 borata-90 cyclopcnta [b]naphtalene sont monocliniques, a = 1 1,8548(4), b = 22,7837(4), c = 8,5457(3) A, P = 106,952(2)", Z = 4, groupe d'espace P2,lrl. On a rdsolu la structure par des mtthodes directes et on l'a affinee par la mtthode des moindres carrts (matrices completes) jusqu'a des valeurs de R = 0,040 et R,.. = 0,047 pour 2970 rtflexions avec I 2 3u(I). On a trouvt que la moltcule est le produit d'addition forinelle entre 1 et PhBO qui a subi une transposition 1.4 du groupement phtnyle du bore au carbone. La base de la moltcule comporte un qystkme replik de trois cycles condensks. La structure comporte la liaison B(.sp3)-~(s~.') la plus longue connue, 1.759(2) A . [Traduit par le journal]

Structural studies of organoboron compounds. XXVI. 8-Methyl-6,6-diphenyl-5,7-dioxa-8-azonia-6-borata-6,7-dihydro-5H-benzocycloheptene

“…A combined theoretical and experi-1 mental approach to the question of the reaction mechanism (2) suggests an intramolecular 1,4-shift of one B-phenyl group occurs. The same type of phenyl group shift has also been observed in the thermal rearrangement of open-chain triphenylborane-adducts of nitrones (1,3). Such a 1,4-migration of a phenyl group in 1 would require a conformation of the sevenmembered ring which would bring one of the phenyl groups close enough to the nitrone group to allow a transition state such as 2.…”

“…The phenylboronate structure of 4 has been I established by an earlier X-ray crystallographic analysis (1).…”

Structural studies of organoboron compounds. LVI. 1-Benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane and 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1.12,6]dodecane

“…In the ( s p 2 )~U~( s p 3 ) anhydridic moiety, the characteristic difference between the very short (sp2)~--0 bond (1.331(2) and 1.329(2) A) and the long (sp3)~--0 bond (1.472(2) and 1.468(2) A) is consistent with that observed for other compounds of type 2 (2), 4 (4), and similar cyclic "pyroboronates" involving one trigonal boronate and one tetracoordinated borinic (1 3) or boronic acid group (14)(15)(16)(17).…”

Structural studies of organoboron compounds XLVIII. 1,4-Diphenyl-3,3:6,6-bis(tetramethylene)-2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane

“…In the present case the short B-C bond is balanced by a relatively long N-B bond. The (sp3)~-C(phen 1) bond length in the phenylboronate compleg 6 (6) of 1.591 1 lies within the range of 1.582 to 1.633 A reported for (sp3)B-C(pheny1) distances in other phenylboronate complexes (17)(18)(19)(22)(23)(24)(25)(26)(27)(28).…”