Neue Bor‐Heterocyclen

Self Cite

Can. J. Chem. 52,2531Chem. 52, (1974. Crystals of 4,4-dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boranatacyclopentane are orthorhombic, a = 17.043(3), b = 6.289(1), c = 13.024(2) A, Z = 4, space group Pna2,. The structure was determined by direct methods, and was refined by filll-matrix least-squares procedures to R = 0.071 for 1100 reflections with I 2 3o(I). Bond angles in the five-membered ring, whlch has a distorted half-chair conformation, range from 101.5(4) for OBO to 107

Section: Introductionmentioning

confidence: 99%

Crystal and Molecular Structure of 4,4-Dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2- boranatacyclopentane

Rettig¹,

Trotter²,

Kliegel³

1974

Self Cite

“…Compared to the hydroxylamines 1, the hydroxymethylamines 4 should be nucleophilic enough to add a second molecule of formaldehyde in a reversible reaction to give the labile intermediate 5 by N-alkylation of the tertiary amine, or an intermediate 7 by 0-alkylation of the zwitterionic form. As reported in a preliminary communication (3), the dialkylamine-bisformaldehyde adducts can also be captured as diphenylboron chelates which are stable crystalline materials. A cyclic B,N-betaine structure 6, derived from the N,N-bisalkylation product 5, has been 'Part XXVII: ref.…”

Section: Introductionmentioning

confidence: 69%

Structural studies of organoboron compounds. XXVIII. 5,5-Trimethylene-2,2-diphenyl-1,3-dioxa-5-azonia-2-boratacyclohexane and 5,5-dimethyl-2,2-diphenyl-1,3-dioxa-5-azonia-2-boratacyclohexane monohydrate

Kliegel¹,

Rettig²,

Trotter³

1988

. 66, 377 (1988).The preparation of the title compounds demonstrates the bis-N-alkylation of secondary amines by formaldehyde, these labile ammonium inner salts being captured as diphenylboron chelates. Crystals of 5,5-trimethylene-2,2;diphenyl-l,3-dioxa-5-azonia-2-boratacyclohexane are orthorhombic, a = 8.8461(3), b = 10.7290(4), c = 15.8773(5) A, Z = 4, space group P212121, and those of 5,5-dimethyl-2,2-diphenyl-1,3-dioxa-5-azonia-2-boratacyclohexane monohydrate are monoclinic, a = 6.2432(3), b = 17.1469(8), c = 14.3701(5) A, P = 90.647(3)", Z = 4, space group P21/n. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.030 and 0.047 for 1400 and 2258 reflections with I ? 3 u ( l ) , respectively. Both compounds have a B,N-betaine structure, the six-membered chelate rings adopting chair conformations. Libration-corrected bond lengths, 0-B = 1.508 (3) [Traduit par la revue] Introduction The alkylation of N,N-dialkylhydroxylamines 1 by formaldehyde leads to labile adducts 2 which can be trapped as diphenylboron chelates 3, as shown for N,N-dimethylhydroxylamine ( I , R = CH3) by an X-ray crystallographic analysis (I). The formal insertion of methylene into 1 results in N-hydroxymethylamines 4 which are also described as zwitterionic primary adducts of formaldehyde and an amine (2). Formaldehyde adducts of dialkylamine (3) are known as very labile compounds2 and exist generally as short-lived intermediates during the formation of enamines, aminals, iminium salts, Mannich bases, or similar compounds. Compared to the hydroxylamines 1, the hydroxymethylamines 4 should be nucleophilic enough to add a second molecule of formaldehyde in a reversible reaction to give the labile intermediate 5 by N-alkylation of the tertiary amine, or an intermediate 7 by 0-alkylation of the zwitterionic form. As reported in a preliminary communication (3), the dialkylamine-bisformaldehyde adducts can also be captured as diphenylboron chelates which are stable crystalline materials. A cyclic B,N-betaine structure

“…Direct N-alkylation and B-arylation of the known (8) compound 112 seemed disadvantageous, so the synthesis of 3 was carried out by N-alkylation of 2-diethylaminoethanol 6 via the addition of oxirane (ethylene oxide) and subsequent trapping of the zwitterionic intermediate 4 as the diphenylboron chelate 3. The symmetrical cyclic B,N-betaine structure 3 has been postulated in a preliminary report (9) on the basis of 'H nrnr data which suggest magnetically equivalent ethylene moieties within the ring skeleton, consistent with the formation of 3 by insertion of oxirane into the N-B bond of compound 5 (9). * Compound 3 is structurally related to the cyclic six-membered B,N-betaines 7 (12) and 8 (13).…”

Section: Introductionmentioning

confidence: 77%

Structural studies of organoboron compounds. XXIX. 6,6-Diethyl-2,2-diphenyl-1,3-dioxa-6-azonia-2-boratacyclooctane monohydrate

Kliegel¹,

Rettig²,

Trotter³

1988

. Can. J. Chem. 66, 109 1 (1988). Details of the preparation and structure of the title compound are given. Crystals of 6,6-diethyl-2,2-diphen 1-1,3-dioxa-6-azonia-2-boratacyclooctane monohydrate are orthorhombic, a = 7.0322(2), b = 16.3505(7), c = 16.8164(4) 1, Z = 4, space group P212121. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.045 and R,, = 0.050 for 2013 reflections with I 2 3 4 4 . The monocyclic eight-membered B, N-betaine is the first to be structurally characterized. The eight-membered chelate ring has a conformation intermediate between the S4 and boat-boat forms which is probably stabilized by transannular C-H...O interactions. The average libration-corrected 0-B and B-C bond lengths of 1.500 and 1.639 A are, respectively, the shortest and longest yet observed for an 0,O-chelate of diphenylboron.WOLFGANG KLIEGEL, STEVEN J. RETTIG et JAMES TROTTER. Can. J. Chem. 66, 1091Chem. 66, (1988. On rapporte les dCtails de la priparation et de la ditermination de la structure du compost mentionne dans le titre. Les cristaux du monohydrate du diCthyl-6,6 diphknyl-2,2 dioxa-1,3 azonia-6 borata-2 cyclooctane sont orthorhombiques avec a = 7,0322(2), b = 16,3505(7) et c = 16,8164(4) A, Z = 4 et groupe d'espace P212121. On a rCsolu la structure par des mkthodes directes et on l'a affinCe par la mCthode des moindres carrCs (matrice entibre) jusqu'a des valeurs de R = 0,045 et R, = 0,050 pour 2013 rkflexions avec I 2 3 4 4 . La B,N-bCtai'ne monocyclique h huit chainons est la premikre a avoir Ct C caracttriste du point de vue de sa structure. Le chtlate cyclique a huit chaions possbde une conformation qui est intermtdiaire entre les formes S4 [Traduit par la revue] Introduction 1,3-Dioxa-6-aza-2-boracyclooctanes 1 are known to undergo intramolecular (transannular) N+B coordination to give very stable bicyclo[3.3 .O]octane ring systems 2, confirmed by chemical and physical investigations (1-6). Generally the extent of the N+B interaction depends on the nitrogen and boron substitution as well as on the conformational conditions. The size and the electronic effects of the substituents markedly influence the magnitude of N-B coordination. In accordance with these findings, replacement of the ring nitrogen atom by oxygen or sulphur led to fairly unstable non-crystalline compounds without any detectable transannular bonding (7).A cyclooctane system without a transannular N 4 B interaction should be realized by quaternization of both the tertiary amine and boronate groups of 1. Direct N-alkylation and B-arylation of the known (8) compound 112 seemed disadvantageous, so the synthesis of 3 was carried out by N-alkylation of 2-diethylaminoethanol 6 via the addition of oxirane (ethylene oxide) and subsequent trapping of the zwitterionic intermediate 4 as the diphenylboron chelate 3. The symmetrical cyclic B,N-betaine structure 3 has been postulated in a preliminary report (9) on the basis of 'H nrnr data which suggest magnetically equivalent ethylene moieties with...