COMMUNICATION Nickel‐catalyzed oxidative esterification of formamides with 1,3‐dicarbonyl compounds under mild reaction conditions Dariush Saberi 1 | Samira Poorsadeghi 2 1 Fisheries and Aquaculture Department, College of Agriculture and Natural Resources, Persian Gulf University, Bushehr 75169, Iran 2 Chemistry Department, Tarbiat Modares University, P.O. Box 14155‐4838, Tehran, Iran Correspondence Dariush Saberi, Fisheries and Aquaculture Department, College of Agriculture and Natural Resources, Persian Gulf University, Bushehr 75169, Iran. Email: saberi_d@pgu.ac.ir Funding information Iran National Science Foundation (INSF), Grant/Award Number: 94015753 Synthesis of enol carbamates was achieved via nickel‐catalyzed oxidative coupling of formamides with 1,3‐dicarbonyl compounds in the presence of tert‐butyl hydroperoxide at 40 °C. Various derivatives of enol carbamates were synthesized by this method in good to excellent yields. KEYWORDS 1,3‐Dicarbonyls, enol carbamates, nickel, oxidative coupling, TBHP 1 | INTRODUCTION Carbamates are important motifs due to their pharmacologi- cal properties such as antibiotic, fungicide, insecticide, and herbicide. [1] Moreover, they are considered as significant synthetic intermediates and protecting groups in chemical industry. [2] Traditionally, synthesis of these compounds is performed via the reaction of amines with phosgene or its derivatives, such as chloroformate, [3] dialkyl carbonates [4] or the reaction of alcohols with isocyanates. [5] However, regarding the toxicity of these reagents and the generation of various by‐products, there is still room for the development of alternative methods. Lately, cross‐dehydrogenative coupling (CDC) has enhanced the efficiency of synthetic procedures leading to C‐O bond formation. [6] These reactions enable one to synthe- size molecules via shorter reaction routes and with higher atom‐economy. [7] Copper‐catalyzed CDC reaction of formamides with suitable precursors for the synthesis of carbamates has been well studied. In 2011, Reddy et al. reported the synthesis of enol carbamates and 2‐carbonyl‐substituted phenol carbamates via the oxidative coupling of formamides with β‐dicarbonyl compounds or ortho‐substituted phenolic com- pounds. [8] They performed these reactions in the presence of copper salts (CuCl 2 or Cu(OAc) 2 ) as the catalyst and TBHP as the oxidant at 80 °C (Scheme 1, Equation 1). Subsequently, Chang et al. conducted these reactions by employment of CuCl/TBHP system at 70 °C which resulted in the same products with excellent yields in a much shorter reaction time. [9] Moreover, copper‐catalyzed oxidative coupling of formamides with salicylaldehydes has already been reported for the synthesis of carbamates (Scheme 1, Equation 2). [10] Nickel, in its elemental form, has lower price than its d 10 ‐block counterparts. Different oxidation states and small atomic radius which lead to short Ni–ligand bond lengths are among other distinctive features of nickel which justify its versatility. [11] Moreover, in contrast to palladium, facile accessibility of Ni(I) and Ni(III) oxidation states allows radical mechanisms in its reactions. [11] All these attributes make Ni a common catalyst in the area of cross‐coupling reactions. [12] In this line of research, we have found that NiCl 2 , a cheap and readily available salt, can be an effec- tive substitute for copper in the synthesis of carbamates, Received: 9 November 2016 Revised: 18 March 2017 Accepted: 25 March 2017 DOI: 10.1002/aoc.3855 Appl Organometal Chem. 2017;e3855. https://doi.org/10.1002/aoc.3855 Copyright © 2017 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/aoc 1 of 6