O–CN Bond Cleavage of Cyanates by a Transition-Metal Complex

Abstract

O−CN bond cleavage of cyanates (ROCN) has been achieved at room temperature in the reaction of ROCN with a methyl Fe, Mo, or W complex. A mechanistic investigation involving DFT calculations revealed that silyl migration from Mo to the CN nitrogen gave an N-silylated η 2 -imidato Mo complex. This intermediate analogue was isolated and characterized by X-ray analysis. Catalytic O−CN bond cleavage was achieved using Cp(CO) 3 MoMe under thermal conditions.

Si–CN Bond Cleavage of Silyl Cyanides by an Iron Catalyst. A New Route of Silyl Cyanide Formation

“…The cycle involves the following steps: (1) dissociation of CO from Fe in [CpFe(CO) 2 Me], (2) oxidative addition of silane, (3) reductive elimination of methane to generate the 16e active species, (4) η 1 -coordination of silyl cyanide to iron, (5) change in the coordination mode from η 1 to η 2 , (6) migration of the silyl group from iron to nitrogen (through a concerted mechanism or a two-step process involving the formation of a pentacoordinated silicon species), (7) cleavage of SiCN bond with migration of the silyl group to the iron center, (8) dissociation of silyl isocyanide, that isomerizes to the thermodynamically more stable silyl cyanide, 2a,3c,18 (9) oxidative addition of a second molecule of silane (R 3 SiH), and (10) reductive elimination of the new silane (R¤ 3 SiH) with regeneration of the active species. This reaction mechanism is similar to that proposed for CCN bond cleavage of organonitriles by an iron complex, 2 and NCN bond cleavage of cyanamides, 3 and OCN bond cleavage of cyanates 4 by a molybdenum complex. The cleavage of the strong SiCN bond is presumably triggered by a silyl migration from iron to nitrogen (step (6) in Scheme 4).…”

“…Finally, CR bond cleavage affords the iron complex bearing silyl isocyanide and R ligands. NCN bond cleavage of cyanamides (R 2 NCN) 3 and OCN bond cleavage of cyanates (ROCN) 3b, 4 have been reported using a molybdenum catalyst, and a catalytic cycle similar to that for CCN bond cleavage has been proposed. In all cases above, the silyl group plays a key role because its migration triggers the cleavage of strong CCN, NCN, and OCN bonds.…”

Synthesis of methacrylate polymer bearing cyanate groups and its chemoselective reaction with amines

“…2‐(4‐Hydroxyphenyl)ethyl methacrylate was prepared from 4‐(2‐hydroxyethyl)phenol and methacryloyl chloride according to the literature . 4‐Cyanatotoluene was prepared from p ‐cresol and cyanogen bromide by the modified procedure of the literature method . The other reagents were used as received.…”

The Construction of X–CN (X=N, S, O) Bonds

“…Organic molecules bearing the O–CN bond (named as cyanate esters) also play irreplaceable roles in synthetic chemistry as well as pharmacy. According to the crystal data, the distance between O and C atom in O–CN is 1.27 Å, which is shorter than traditional O–C single bond . Thus, the O–CN bond is considered to be much stronger, and more difficult to be activated.…”

“…[50] Thus,t he O-CN bondi sc onsidered to be much stronger,a nd more difficult to be activated.D elightfully,w ith the greate fforts of organic chemists,c yanates could be successfully useda se fficient cyano source. [50] Thus,t he O-CN bondi sc onsidered to be much stronger,a nd more difficult to be activated.D elightfully,w ith the greate fforts of organic chemists,c yanates could be successfully useda se fficient cyano source.…”