Carbon isotope labeling of carbamates by late-stage [¹¹C], [¹³C] and [¹⁴C]carbon dioxide incorporation

Abstract

A general procedure for the late-stage [11C], [13C] and [14C]carbon isotope labeling of cyclic carbamates is reported. This protocol allows the incorporation of carbon dioxide, the primary source of carbon-14...

Interrupted aza-Wittig reactions using iminophosphoranes to synthesize 11C–carbonyls

“…We next investigated the scope of functionalized aryl iminophosphoranes synthesized by the Kirsanov reaction and isolated by our modified general procedure (Scheme 2c, see ESI for details). 18 First, CBz-protected products (17)(18)(19)(20)(21) were isolated to determine sensitivity to electronic and steric features of iminophosphoranes under the optimized conditions. Electron-rich arenes, aryl bromides, and ortho-substitution (17)(18)21) were all well-tolerated in comparison with electron-deficient iminophosphoranes (19)(20).…”

“…18 First, CBz-protected products (17)(18)(19)(20)(21) were isolated to determine sensitivity to electronic and steric features of iminophosphoranes under the optimized conditions. Electron-rich arenes, aryl bromides, and ortho-substitution (17)(18)21) were all well-tolerated in comparison with electron-deficient iminophosphoranes (19)(20). Alkyl iminophophosphoranes afforded products such as carbamate 22 (82%) and blocked isocyanates 23-24 in good yields.…”

“…19 Del Vecchio et al deployed o-azidoanilines and azido alcohols with dimethylphenylphosphine to synthesize cyclic ureas and carbamates, including oxatomide, domperidone, and zolmitriptan in useful yields through a proposed intramolecular Staudinger aza-Wittig sequence (SAW, Scheme 1a) upon heating to 70 °C. 20,21 An intermolecular variant of this reaction produced a linear carbamate in low RCY at much higher temperature.…”

Interrupted Aza-Wittig Reactions Using Iminophosphoranes to Synthesize 11C-Carbonyls

“…We next investigated the scope of functionalized aryl iminophosphoranes synthesized by the Kirsanov reaction and isolated by our modified general procedure (Scheme 2c, see ESI for details). 18 First, CBz-protected products (17)(18)(19)(20)(21)…”

Photochemical Strategy for Carbon Isotope Exchange with CO2

“…In the last couple of years, late-stage 14 C-labeling has undergone sudden growth . In particular, carbon isotope exchange (CIE), which allows for the 12 C– 12 C bond cleavage and 12 C– 14 C bond formation in one single step, emerged as a privileged strategy (Figure B) .…”