331983-64-3

Upstream product

• 108129-49-3 N-benzoyloxyurea 
• 320778-07-2 1-acetyl-4-phenyl-imidazolidin-2-one 
• 61337-91-5 (R)-N¹-methyl-1-phenylethane-1,2-diamine 
• 57-13-6 urea 

Relevant academic research and scientific papers

Enantioselective Ring-Closing C–H Amination of Urea Derivatives

An enantioselective intramolecular C(sp3)–H amination of N-benzoyloxyurea by using a chiral-at-metal ruthenium catalyst is reported, providing chiral 2-imidazolidinones in yields of up to 99percent and with up to 99percent ee. Catalyst loadings down to 0.05 mol percent are feasible. Control experiments support a stepwise nitrene insertion mechanism through hydrogen atom transfer of a ruthenium nitrenoid intermediate followed by a radical recombination. Chiral 2-imidazolidinones are prevalent in bioactive compounds and can be converted to chiral vicinal diamines in a single step. The synthetic value of the new method is demonstrated for the synthesis of intermediates of the drugs levamisole and dexamisole, the bisindole alkaloids topsentine D and spongotine A, and a chiral organocatalyst. Direct C–H functionalization offers the prospect for streamlined synthesis with high atom economy. In this respect, the transition-metal-catalyzed enantioselective insertion of nitrenoids into prochiral sp3 C–H bonds is a powerful tool for the efficient construction of non-racemic chiral nitrogen-containing molecules. Intramolecular versions have been used to synthesize chiral nitrogen heterocycles, but cyclic urea is still elusive through enantioselective nitrenoid insertion chemistry. Here, we fill this gap and report an enantioselective intramolecular C(sp3)–H amination of N-benzoyloxyurea to provide chiral 2-imidazolidinones in high yields and with high enantioselectivities. The synthetic utility of this new method is illustrated with the catalytic asymmetric synthesis of medicinal agents, natural products, and a chiral organocatalyst. Our work emphasizes the usefulness of transition-metal-controlled asymmetric nitrene chemistry and the importance of tailored catalyst design. Here, we report the first catalytic asymmetric ring-closing C(sp3)–H amination of urea derivatives to construct chiral 2-imidazolidinones, which are prevalent in bioactive compounds and can be converted to chiral vicinal diamines. The simple and mild transformation is catalyzed by a recently developed chiral-at-ruthenium complex in high yields and with high enantioselectivities. Applications to the drugs levamisole and dexamisole, the bisindole alkaloids topsentine D and spongotine A, and a chiral organocatalyst demonstrate the synthetic value of this new method.

The preparation of imidazolidinone and oxazolidinone chelated carbene complexes

The synthesis of several internally chelated imidazolidinone and oxazolidinone Fischer carbene complexes of the type (CO)4M=CC(R1)NCO(CHR2CHR3X) are reported where the M=chromium, tungsten; R1=methyl, ethyl, iso-propyl, phenyl, trans-propenyl, iso-propenyl, iso-butenyl, cyclohexenyl and 1-propynyl; R2=H, Ph, Bn, Me, Cy; R3=H, Me, Ph; X=O, NMe. Four different methods are used for the synthesis of these complexes. The imidazolidinone complexes are best prepared by adding an imidazolidinone or lithiated imidazolidinone to a methoxy carbene complex or to an in-situ generated acetoxy carbene complex. α,β-Unsaturated imidazolidinone complexes are prepared by aldol condensations of alkyl imidazolidinone complexes or by alkylaltion of these complexes with bromomethyl methyl ether and then elimination of methanol. The oxazolidinone complexes are best made by a two-step procedure that involves the addition of an β-aminoalcohol to a methoxy or acetoxy complex followed by closure of the resulting amino carbene complex to the oxazolidinone complex with phosgene.

Chiral-at-Ruthenium Catalysts with Mixed Normal and Abnormal N-Heterocyclic Carbene Ligands

We recently reported a new class of chiral ruthenium catalysts in which two achiral bidentate N-(2-pyridyl)-substituted N-heterocyclic carbene ligands in addition to two labile acetonitriles are coordinated to a central ruthenium and generate a stereogenic metal center which is responsible for the overall chirality (Zheng et al. J. Am. Chem. Soc. 2017, 139, 4322). Here we now report our discovery of related chiral-at-ruthenium catalysts in which normal and abnormal N-heterocyclic carbene (NHC) ligands are present at the same time. The synthesis of racemic complexes, their resolution into individual enantiomers by a chiral auxiliary approach, and a catalytic application are reported. The mixed normal/abnormal NHC complexes display significantly increased turnover numbers and turnover frequencies for a nitrene-mediated enantioselective C(sp3)-H amination.

An unusual enhancement of chiral induction by chiral 2-imidazolidinone auxiliaries

Diastereoselectivity which is induced by the use of 2-imidazolidinone auxiliaries is greatly dependent on the N-substituents of the heterocycles, among which the bulky arenesulfonyl group is the moiety of choice. Reactions of this type afford an excellent level of diastereoselection in the methylation of N'-butyryl-2-imidazolidinones via the metal enolates. (C) 2000 Published by Elsevier Science Ltd.