9‐Arsaanthracene

Abstract

The "best" plane through C(3)-C(7)-0(1)-N is at an angle of 18 to the f3-lactam ring, and at an angle of 41 to the benzene ring. The lactam ring and benzene ring are inclined at an angle of 56 to each other. The deviation of the molecule from the favorable planar resonance form appears to be due to steric factors. The hydrogen atom on C(2) approaches to within 2.75 A of 0(2), that on C(4) to within 2.71 A of O(1); on the other hand the sum of the van der Waals radii in both cases is 2.7 A. A few Characteristic bond lengths (in A) are given in the Figure (average standard deviation: 0.01 5 A). Particularly striking is the large distance between C(8) and C(9), which has also been observed in another p-lactarn161. The C(10)-0(2) distance is unusually small for a carbon-oxygen double bond; this is also apparent from the carbonyl stretching vibration at 5.62 pm.

From a 2,1‐Benzazaarsole to Elusive 1‐Arsanaphthalenes in One Step

“…The CH!NH protonm igration necessary for the formation of 2b and 3b (Scheme 1) was reflected in 1 H and 13 C{ 1 H} NMR spectra. Thus, 1 HNMR spectra lacks ignals of the (CH)N moiety but contain as ignal attributable to an ewly formed C(NH)g roup at d = 8.49 and 6.18 ppm for 2b and 3b, respectively.T he 1 H, 15 NH MBC spectra showedd oubletsf or the NHg roup at d = À294 and À296 ppm with at ypical 1 J( 1 H, 15 N) = 89 Hz. Consequently,t he signal of C(NH) is shiftedt ot he region typical for sp 2 -carbona toms (d = 117.6 and 123.6 ppm, for 2b and 3b,r espectively).…”

Arsenic Compounds

“…The Grignard reagent is the organometallic compound most widely employed in these syntheses (39). Organolithium (40), organoaluminum (41), organotin (42), organocadmium (43), and organomercury (44) compounds have also been employed. Some triarylarsines (Ar 3 As) can be prepared by the sodium-promoted interaction of an aryl halide and an arsenic trihalide (AsX 3 ) (45): This type of reaction is sometimes considered a variant of the Wurtz-Fittig reaction.…”

“…The alkylation of arsenic trihalides with organometallic reagents is another method of preparing halo and dihaloarsines. The metals used in these syntheses include tin (42), cadmium, lithium, zinc, aluminum, and magnesium. These reactions are not commonly employed because they often give mixtures of haloarsines, dihaloarsines, and tertiary arsines.…”

Clicking the Arsenic–Carbon Triple Bond: An Entry into a New Class of Arsenic Heterocycles

“…In this respect, the chemistry of so-called low-coordinate arsenic compounds has been investigated to some extent during the last few decades, but this field is certainly dominated by their unsaturated organophosphorus congeners. [4] Ashe III finally prepared the more stable and aromatic parent arsinine C 5 H 5 As (C, R = H) in 1971. With the synthesis of arsamethine-cyanines (A), Märkl and Lieb reported the first evidence of the existence of this type of bonding in 1967.…”

“…[3] By integrating the As = C bond into an aromatic system, Jutzi and Bickelhaupt accessed the highly reactive 9-arsaanthracene (B). [4] Ashe III finally prepared the more stable and aromatic parent arsinine C 5 H 5 As (C, R = H) in 1971. This was followed by the even more kinetically stabilized aryl-substituted arsinines by Märkl et al in 1983.…”