Functionalized oxazoles from rhodiumi-catalyzed reaction of dimethyl diazomalonate with nitriles

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

“…Later Helquist and Åkermark used Rh-catalysts for this transformation, which allowed to obtain oxazoles in higher yields under mild conditions. 522 This chemistry was extensively developed by Åkermark, 523 Xu, 524 Moody, 525 Yoo, 526 Ibata, 527 Marsden, 528 and Zhu, 529 . The reaction proceeds via formation of the Rh-carbenoid 5-25, which undergoes a nucleophilic attack by the nitrile to form ylide intermediate 5-26 , which cyclizes into oxazole 5-24 (Scheme 339).…”

Transition‐Metal‐Catalyzed Denitrogenative Transannulation: Converting Triazoles into Other Heterocyclic Systems

“…[25] According to the path a in Scheme 9, a nuclephilic attack of the nitrile on the rhodium carbenoid 20 [26] leads to the ylide 23 , which upon cyclization into the zwitterion 24 and subsequent loss of the metal, furnishes the imidazole 22 . Alternatively, ylide 23 may give rise to the rhodium carbenoid 25 through a [1,3] Rh shift.…”

I–‐Catalyzed Reaction of 5‐Methoxyoxazoles with Organic Iodides – An Efficient Synthesis of Azalactones

“…Solid, m.p. 91-93°C (petroleum ether/ ethyl acetate) (98-99°C [10] [9] The reaction of dimethyl 2-diazomalonate (1.58 g, 10 mmol), acetonitrile (0.83 g, 20 mmol), and Rh 2 (OAc) 4 (22 mg + 22 mg, 0.1 mmol) in CHCl 3 (10 mL) afforded 1.09 g (63 %) of 1d. Solid, m.p.…”