Recent advances in decarboxylative nitration of carboxylic acids (original) (raw)
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A Nitro-Hunsdiecker Reaction: From Unsaturated Carboxylic Acids to Nitrostyrenes and Nitroarenes
Organic Letters, 2002
The nitrodecarboxylation of aromatic r,-unsaturated carboxylic acids and ring-activated benzoic acids can be achieved using nitric acid (3 equiv) and catalytic AIBN (2 mol %) in MeCN. From the effect of various additives, the nitrodecarboxylation is postulated to involve the generation of an acyloxy radical RCO 2 • by a NO 3 • radical followed by attack of a NO 2 • radical.-Nitrostyrenes are versatile building blocks in organic synthesis. 1,2 They are generally prepared by the condensation of aldehydes with nitroalkanes, the Henry reaction, or by the nitration of styrenes. Our recent success in catalytic halodecarboxylation reaction of unsaturated carboxylic acids 3 prompted us to find a gateway into nitrostyrenes and nitroarenes via the nitrodecarboxylation reaction (Scheme 1). Bachman et al. showed that under high dilution conditions, acyl nitrates, RC(dO)ONO 2 , could be generated from aliphatic carboxylic acids with little or no danger of explosion. Nitrodecarboxylation of acylnitrates was accomplished satisfactorily at the optimum temperature range of 270-300°C to provide nitroalkenes in good yields. 4 However, under similar conditions, aromatic carboxylic acids gave 11-23% of nitroarenes. More recently, nitrodecarboxylation of benzoic acids with N 2 O 5-HNO 3 , AcOH-HNO 3 , and NO 2 X-HNO 3 is reported. 5,6 Prior to 1960, the reaction of styrenes and acrylic acids was carried out by a wide variety of nitrating agents. 7 Rationalization of the reactions was complicated by diverse distribution of products. Subsequent literature is testimony to the reagent-selective product formation in the nitration of styrenes. Only in a few cases are-nitrostyrenes obtained as the major or minor products. 8 To our knowledge, in no case is a nitrodecarboxylation observed. This has now been realized in the case of aromatic R,-unsaturated carboxylic acids using nitric acid (3 equiv) and catalytic azobisisobutyronitrile (AIBN). Taking 4-methoxycinnamic acid 1 as the model substrate, we carried out a number of optimization experiments. Comparison of data, particularly for the first 1 h of the (1) (a)
A novel, mild and convenient method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their nitroolefins is achieved using a catalytic amount of CuCl (10 mol%) and tertbutyl nitrite (2 equiv.) as a nitrating agent in the presence of air. This reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives, which are generally difficult to access from other conventional methods. Additionally, this reaction is selective as the E-isomer of the acid derivatives furnishes the corresponding E-nitroolefins. One more salient feature of the method is, unlike other methods, no metal nitrates or HNO3 are employed for the transformation.
Synthesis of (E)-nitroolefins via decarboxylative nitration using t-butylnitrite (t-BuONO) and TEMPO
Chemical Communications, 2013
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Nitrocompounds as useful reagents for the synthesis of dicarbonyl derivatives
Arkivoc, 2006
The reaction of functionalized nitroalkanes with electrophiles such as Michael acceptors and aldehydes is one of the most exploited procedures for the synthesis of new carbon-carbon bonds. Conversion of the nitro group in the adduct into a carbonyl derivative usually provides a rapid entry to dicarbonyl systems that are amenable to further synthetic transformation into a plethora of important targets. oxidative, reductive, as well as almost neutral, conditions. The aim of this review is to discuss the utilization of nitroalkanes as nucleophilic reagents for the synthesis of dicarbonyl derivatives using a strategy involving a nucleophilic addition of the nitro derivative followed by a nitro to carbonyl conversion. Although these procedures are usually accomplished by a two-step synthesis, there are several examples in which this overall transformation can be carried out in a 'one-pot' system thus realizing a more efficient process.
A New, One Pot Synthesis of Alkylated Methyl Tri- and Tetracarboxylate Derivatives by Nitrolkanes
Synthesis, 2004
The reaction of nitroalkanes with trimethyl trans-aconitate in acetonitrile, in the presence of DBU as base, allows the one pot formation of alkylated methyl tri-and tetralkanoate derivatives via base induced nitrous acid elimination. The title compounds can also be obtained, in one flask, starting with the reaction of methyl nitroacetate with dimethyl maleate, followed by the addition, in the same flask of the nitroalkane.
Recent Advances in Decarboxylative Reactions of Alkynoic Acids
Idris, M. A.; Lee, S. Synthesis-Stuttgart, 2020, 52 (16), 2277-2298, 2020
Alkynoic acids have been widely employed as alkyne and alkene sources in decarboxylative reactions. Alkynoic acid coupling leads to the formation of direct coupling products and cyclized products through sequential reactions. Moreover, homocoupling and multicomponent reactions have been developed. The decarboxylative addition of alkynoic acids generates the corresponding alkene products. A number of synthetic methods are utilized for the preparation of arylpropynoic acids including the Sonogashira coupling and the carboxylation of terminal alkynes. Recently, the use of decarboxylative halogenations has also been reported. This review covers decarboxylative reactions of alkynoic acids reported between 2013 and 2019; further, it is divided into several sections according to the type of reaction.