Ferdinand Bosold

The Crystal Structures of a Lower Order and a “Higher Order” Cyanocuprate: [tBuCu(CN)Li(OEt2)2]∞ and [tBuCutBu{Li(thf)(pmdeta)}2CN]

Different types of bonding are present in cyanocuprates 1 and 2, whose crystal structures could be determined (the drawings below show the important structural characteristics). Accordingly, 1 is a lower order cyanocuprate of the type RCu(CN)Li, whereas 2, which is of the type R2 Cu(CN)Li2 , does not exist as a higher order cyanocuprate with Cu-CN bonds, but rather as a cyano-Gilman cuprate.

The relation between ion pair structures and reactivities of lithium cuprates

From Li+ well-solvating solvents or complex ligands such as THF, [12]crown-4, amines etc., lithium cuprates R2CuLi(*LiX) crystallise in a solvent-separated ion pair (SSIP) structural type (e.g. 10). In contrast, solvents with little donor qualities for Li+ such as diethyl ether or dimethyl sulfide lead to solid-state structures of the contact ion pair (CIP) type (e.g. 11). 1H,6Li HOESY NMR investigations in solutions of R2CuLi(*LiX) (15, 16) are in agreement with these findings: in THF the SSIP 18 is strongly favoured in the equilibrium with the CIP 17, and in diethyl ether one observes essentially only the CIP 17. Salts LiX (X=CN, Cl, Br, I, SPh) have only a minor effect on the ion pair equilibrium. These structural investigations correspond perfectly with Bertzs logarithmic reactivity profiles (LRPs) of reactions of R2CuLi with enones in diethyl ether and THF: the faster reaction in diethyl ether is due to the predominance of the CIP 17 in this solvent, which is the reacting species; in THF only little CIP 17 is present in a fast equilibrium with the SSIP 18. A kinetic analysis of the LRPs quantifies these findings. Recent quantum-chemical studies are also in agreement with the CIP 17 being the reacting species. Thus a uniform picture of structure and reactivity of lithium cuprates emerges.

SN2 at nitrogen: The reaction of N-(4-cyanophenyl)-O-diphenylphosphinoylhydroxylamine with N.Methylaniline. A model for the reactions of ultimate carcinogens of aromatic amines with (bio) nucleophiles

The model reaction of 5 with 6 to give 7 and 8 (t-90%) follows the SN2 mechanism. From this result and from product studies it is concluded that the reactions of the ultimate carcinogen 1 with 6 and deoxyguanosine (dG) (and hence d other ultimate carcinogens of aromatic amines with bionucleophiles) follow the same mechanism.

Die Kristallstrukturen eines Lower-order- und eines „Higher-order”-Cyanocuprates: [tBuCu(CN)Li(OEt2)2]∞ und [tBuCutBu{Li(thf)(pmdeta)2CN}]

Deutlich verschieden sind die Bindungsverhaltnisse in den Cyanocupraten 1 und 2, deren Kristallstrukturen jetzt bestimmt wurden (die Strichformeln unten zeigen die wesentlichen Strukturmerkmale). Demnach ist 1 ein Lower-order-Cyanocuprat des Typs RCu(CN)Li. Das Cuprat 2 des Typs R2Cu(CN)Li2 liegt nicht als „Higher-order”-Cyanocuprat mit einer Cu-CN-Bindung vor, sondern als Cyano-Gilman-Cuprat.

Synthesis of N-acetoxy-2-aminonaphthaline, an ultimate carcinogen of the carcinogenic 2-naphthylamine, and its in vitro reactions with (bio)nucleophiles

Abstract In this communication we describe (1) the synthesis of N-acetoxy-2-aminonaphthaline 4a (an ultimate carcinogen of the carcinogenic 2-naphthylamine), of N-pivaloyloxy-2-aminonaphthaline 4b , and (2) the reactions of 4a(b) with the nucleophiles N-methylaniline 6 and deoxyguanosine 7 . Of special interest is the formation of the deoxyguanosine “adducts” 12 – 14 . In this communication we described (1) the synthesis of N-acetoxy-2-aminonaphthaline 4a (an ultimate carcinogen of the carcinogenic 2-naphthylamine), of N-pivaloyloxy-2-aminonaphthaline 4b , and (2) the reactions of 4a(b) with the nucleophiles N-methylaniline 6 and deoxyguanosine 7 . Of special interest is the formation of the deoxyguanosine “adducts” 12 – 14 .

Electrophilic amination of acyl anion equivalents: mild oxidation of aldehydes to amides via 0-(trimethylsilyl)aldehyde cyanohydrin anions

Abstract The O-(trimethysilyl)aldehyde cyanohydrin anions 4a–p bm Li ⊕ react with 5 to the amines 6 . This electrophilic amination corresponds to a mild and specific oxidation of the aldehydes 1a–p to the amides 7a–p.

Formation of acceptor substituted phenylnitrenes via α-elimination under mild conditions

Abstract The acceptor substituted 1a-d and 2d react with n-butylamine to give 5, 6 and 7. This strongly suggests the intermediate formation of substituted phenylnitrenes via α-elimination.

Crystal Structure of [2-ZnCl-benzoxazole⋅2 THF]2: The Remarkable Difference between 2-ZnHal- and 2-Li-oxazoles

The strong influence of the metal (M) on the equilibrium 1-M⇌2-M (shown below) is clearly evident: it is far towards the 2-M side with M = Li, whereas it is on the 1-M side for M = ZnCl. The first crystal structure of a 2-metalated oxazole, [3-ZnCl⋅2u2009THF]2 (below right), has been determined.

Crystal structure of 1-lithio-1-phenyl-2,2-dimethylhydrazinetetrahydrofuran, [(C6H5)(CH3)2N2]Li·C4H8O

Source of material: see ref. 1. A high air and moisture sensitive crystal was mounted in a capillary under argon atmosphere. Lithiated (alkali metallated) hydrazines are of interest because of their relation to Li-amides (see refs. 1 ,2) . W e were interested in the structure of these compounds because of their relation to a-lithiated ethers (see refs. 3, 4) and amines (see ref. 5), and iV-lithiated hydroxylamines (nitrenoids, see ref. 6).