New Catalyzed Three‐Component Cycloadditions for the Synthesis of Eight‐Membered Carbocycles

Abstract

The sum always amounts to eight—Two new three‐component [m+n+o] cycloadditions offer novel synthetic routes to eight‐membered carbocycles (see scheme; m, n, o=4, 2, 2 or 5, 2, 1). The rhodium center serves as a template and brings three components into the necessary arrangement for the desired cycloaddition, thus enabling difficult‐to‐form eight‐membered carbocyclic rings to be constructed in a single chemical operation with good atom economy.

Iron nitrate/TEMPO-catalyzed oxidative Passerini reaction of alcohols in air

“…In summary, we have demonstrated that the Fe(NO 3 ) 3 .9H 2 O/TEMPO is an effective homogenous catalyst system for oxidative 3C-Passerini reaction using air as oxidant. This catalytic system does not require any additive and the reaction has broad substrate scope across all three components.…”

“…To a flask charged with DCE (5 mL) were added benzyl alcohol 1a (0.1 g, 0.92 mmol), benzoic acid 2A (0.124 g, 1.02 mmol) and tert-butylisocyanide 3a (115 µL, 1.02 mmol) at room temperature under air (maintained by air balloon). Thereafter, Fe(NO 3 ) 3 .9H 2 O (0.037 g, 0.092 mmol) and TEMPO (0.014 g, 0.092 mmol) were added and the mixture was stirred at room temperature for 24 h. After completion of reaction (as monitored by TLC), the solvent was evaporated and the residue was extracted with EtOAc (15 mL x 2) and water (25 mL). The organic layers were pooled, dried over Na 2 SO 4 and evaporated to obtain the crude product.…”

“…44 Subsequently we reported the suitability of this catalyst system for oxidative 3C-Ugi reaction using arylmethyl amines as the imine precursors. 45 In continuing studies related to the use of Fe(NO 3 ) 3 .9H 2 O/TEMPO for oxidative reactions, we sought investigating its potential for oxidative 3C-Passerini reaction. It is worth mentioning that Fe(NO 3 ) 3 .9H 2 O/TEMPO system has been reported to be excellent catalyst for the oxidation of alcohols to aldehydes under aerobic conditions.…”

Multicomponent Reactions in the Total Synthesis of Natural Products

“…Recently, Lindsley and co-workers reported a threecomponent condensation to polysubstituted triazines, which were used as precursors to the skeleton of canthine alkaloids [141]. As exemplified by recent reports from the research groups of Wender [142], Montgomery [143], Ikeda [144] and Murakai [145] several transition metal-promoted MCRs have also demonstrated undeniable potential towards the formation of medium and strained bicyclic ring structures reminiscent of specific families of natural products. It seems only a matter of time before these powerful processes become commonly used in the total synthesis of complex natural products.…”

One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides to N-alkyl-2-(2-hydroxyphenyl)-2-imino-acetamides

“…Multicomponent reactions (MCRs) [1][2][3][4][5] in general and isocyanide-based multicomponent reactions (IMCRs) [6][7][8][9][10] in particular have attracted the attention of chemist's during the past years. These reactions are well defined and suited for combinational library synthesis due to the fact that products are formed in one-pot reactions [11][12].…”