Isocyanide adducts

The first stable group 14 heteroallene, a l-stannaketenimine (99), was reported by Griitzmacher et al. in 1992." Compound 99 was synthesized in 9 % yield by adding diarylstannylenc 97 and mesityl isocyanide 98 in hexane (Eq. (12)). The bonding in 99 can be described as a stannylene-isocyanide adduct rather than a... 

Triorganoboron complexes of Af,0-heterocyclic carbenes are also known (36). Thus, triphenylboron-carbene complex 48 can be isolated from the reaction of methanol with an isocyanide adduct of BPh3 (47) in the presence of a catalytic amount of KF. The X-ray crystal structure of 48 demonstrated that the boron atom is tetrahedrally coordinated and that all four B-C bond distances are equal within experimental error. 

These materials are characterized by common techniques such as H NMR, IR, elemental analysis, DSC, and TGA.54 58 59 60 64 68 Other techniques such as electron spin resonance (ESR),54 magnetic susceptibilities54 and Mossbauer spectroscopy (when they apply),56,58 60 64 71 uV-visible spectroscopy,58,59 60 61 64-67 and solid-state electric conductivity measurements5456 59-63 66 67 71 were also employed. These materials were carefully compared to model bis(mono-isocyanide) adducts for better understanding of the physical properties. Important solubility problems are often observed when no alkyl side chain is used. So, these more soluble substituents are incorporated either on the macrocycles or the bridging ligands for better characterization. 

Bis(trjfluoromethyl)keten reacts with isocyanides and with diazomethane (as methylene) to afford dialkylidenedioxolanes by pathways presumed to begin with isocyanide or methylene attacking the carbonyl group. The 2 1 isocyanide adducts were identified by hydrolysis to pyruvate amides, as well as by spectroscopy (see Scheme 47). 

Table 12. H-NMR data of some bis-isocyanide adducts of iron(II)-tetrapyrrole chelates...

Kulkarni NV, Das A, Jayaratna NB, Yousufuddin M, Rasika Dias HV. Zinc-mediated carbene insertion to C-Cl bonds of chloromethanes and isolable zinc(II) isocyanide adducts. Inorg Chem. 2015 54 5151-5153. 

C32H4iBrN20i2f Dimethyl acetylenedicarboxylate-cyclohexyl isocyanide adduct, 37B, 161... 

Extensive H NMR studies have been done with the cyclohexyl isocyanide adducts of CpsLn. In the case of the praseodymium complex, while at room temperature rapid inversion of the cyclohexyl ring gives rise to 7 discrete cyclohexyl proton resonances, by lowering the temperature ( 70 C) it has been possible to detect all 13 possible signals for the two slowly inverting conformers (AG for the ring inversion=282 15 cal/mole) (Von Ammon et al. 1971). The electronic structure of CpsLn adducts has been studied by Amberger and Schultze (1987). 

Fifty years of established views of the Ugi reaction have been challenged by results of a theoretical study which suggests, for example, that the intermediate imine is not in equilibrium with its isocyanide adduct." An asymmetric three-component Ugi reaction has applied chiral cyclic imines in synthesis of morpholino- or piperazine-keto-carboxamide derivatives." ... 

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