One-Pot Synthesis of Aza-Diketopiperazines Enabled by Controlled Reactivity of N-Isocyanate Precursors
摘要:
A one-pot sequence for the synthesis of aza-diketopiperazines is reported, involving carbazate acylation with chloroacetyl chloride, S(N)2 with a primary amine, N-isocyanate formation, and cyclization. Nitrogen-substituted isocyanates (N-isocyanates) are a rare class of amphoteric isocyanate with high, but severely underdeveloped synthetic potential. This approach highlights that beta N-acyl carbazates can act as blocked (masked) N-isocyanates, thus allowing a challenging intermolecular S(N)2 reaction of a primary amine to proceed while the N-isocyanate is "protected", and then cydization once it is unmasked. Control experiments show that the alternate pathway-N-isocyanate substitution and then cydization by an intramolecular S(N)2 reaction-is not operating.
Cascade reactions of nitrogen-substituted isocyanates: a new tool in heterocyclic chemistry
作者:Jean-François Vincent-Rocan、Ryan A. Ivanovich、Christian Clavette、Kyle Leckett、Julien Bejjani、André M. Beauchemin
DOI:10.1039/c5sc03197d
日期:——
In contrast to normal C-substituted isocyanates, nitrogen-substituted isocyanates (N-isocyanates) are rare. Their high reactivity and amphotheric nature has prevented the scientific community from exploiting their synthetic potential. Recently, we have...
A Cascade Synthesis of Aminohydantoins Using In Situ-Generated<i>N</i>-Substituted Isocyanates
作者:Jean-François Vincent-Rocan、Christian Clavette、Kyle Leckett、André M. Beauchemin
DOI:10.1002/chem.201405648
日期:2015.3.2
building blocks for the development of cascade reactions in heterocyclic synthesis. These reactive amphoteric intermediates can be accessed in situ via an equilibrium that allows controlled reactivity in the presence of bifunctional partners such as α‐amino esters. A cascade reaction has been carried out that forms 3‐aminohydantoin derivatives using simple phenoxycarbonyl derivatives of hydrazides and