3‐Aminoidoles, Imidazolidines, and Oxazolidines from Isocyanides and Carbene Complexes by Metal‐Induced [4+2]‐ and [3+2]‐Cycloadditions

Abstract

Carbene complexes 1 react with isocyanides 2 to give ketenimine complexes 312' in good yields. Complexes 3 prove to be versatile synthons for organic reactions. [',41 They are capable of undergoing novel [2 + 2]-, [31 [3 + 21-, and [4 + 21-cycloadditions, all of which are characteristically controlled by the carbonylmetal fragment.H,, 2-Thienyl; R' = CeH,. o-CH~O-C~HI. c-C~H,, In inert solvents, 3 is slowly converted at 40-70°C into 1,2-bis(imino)cyclobutane complexes 5 and M(C0)6 by a template-controlled symmetric [2 + 21-cycloaddition of two C=C bonds, presumably via the intermediates 4.['] 4 5 3a reacts rapidly with the C=O and C=N-groups of aldehydes 6a and isocyanates 6b, respectively, undergoing [3 + 21 c y~l o a d d i t i o n~~~ to give the oxazolidine complexes 7a-c and imidazolidine complexes 7d-i, respectively. In each case formation of a M = C bond to the central C atom of the CCN moiety takes place (Table 1). 9s c-C6H,, 6

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…A reaction analogous to the formation of 145 has been described by Aumann et al (see Scheme ). Tungsten−ketenimine complexes 153 , obtained by insertion of aliphatic isonitriles into the metal−carbon double bond of Fischer carbene complexes, ,, react with the CO and CN groups of aldehydes, isocyanates or carbodiimides to give oxazolidine or imidazolidine complexes 155 .…”

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

“…[632] The keteneimine complexes (OC) 5 M{η 1 -N(R 1 )=C=C(OEt)R 2 (M = Cr, Mo, W) undergo [3+2]-cycloaddition reactions with the C=O and C=N groups of aldehydes and isocyanates to give oxazolidine-4-ylidene or imidazolidine-4-ylidene-2-one complexes, e.g., 156. [633] The nitrile imine PhCϵN-NPh was added to the C-S bond of coordinated CS 2 to afford the 1,3,4-thiadiazoline-2-thione complex 157. [634] Cycloaddition reactions of alkynyl, allyl and propargyl organometallics have been covered in several reviews.…”