Microwave-assisted palladium-catalysed isonitrile insertion in 2-bromophenylureas for efficient synthesis of 4-substituted imino 4H-benzo[d][1,3]oxazin-2-amines

Pandey, Garima; Batra, Sanjay

doi:10.1039/c5ra03062e

Cited by 9 publications

(3 citation statements)

References 27 publications

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“…It should be noted that similar one-pot hydroxyimidoylation/cyclization cascades are also reported in the syntheses of indolin-1-ones [45] and fused dihydropyrrolimines [46]. In a related process, the cyclooxyimidoylation of (2-bromoaryl)ureas 67 proceeds with full selectivity to the urea oxygen, which results in iminobenzoxazinones 68 (Scheme 21) [47]. In contrast In a related process, the cyclooxyimidoylation of (2-bromoaryl)ureas 67 proceeds with full selectivity to the urea oxygen, which results in iminobenzoxazinones 68 (Scheme 21) [47].…”

Section: Cross-couplings With Oxygen or Nitrogen Nucleophilesmentioning

confidence: 60%

“…In a related process, the cyclooxyimidoylation of (2-bromoaryl)ureas 67 proceeds with full selectivity to the urea oxygen, which results in iminobenzoxazinones 68 (Scheme 21) [47]. In contrast In a related process, the cyclooxyimidoylation of (2-bromoaryl)ureas 67 proceeds with full selectivity to the urea oxygen, which results in iminobenzoxazinones 68 (Scheme 21) [47]. In contrast to the couplings above, this transformation is highly compatible with various isocyanides, as aliphatic, α-acidic, and aromatic isocyanides all afford the iminobenzoxazinones 68 in high yields, regardless of the isocyanide substituent.…”

Section: Cross-couplings With Oxygen or Nitrogen Nucleophilesmentioning

confidence: 99%

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Recent Advances in Palladium-Catalyzed Isocyanide Insertions

et al. 2020

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Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.

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Section: Cross-couplings With Oxygen or Nitrogen Nucleophilesmentioning

confidence: 60%

Section: Cross-couplings With Oxygen or Nitrogen Nucleophilesmentioning

confidence: 99%

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

et al. 2020

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“…The three-component synthesis of 4-imino-4H-3,1-benzoxazines (24) was developed by Zhu 21 and co-workers in 2005. Heating a toluene solution of an aldehyde (23), an amine (22), and an isonitrile (21) in the presence of stoichiometric amount of ammonium chloride produced the title compound in good to excellent yields (Scheme 4).…”

Section: Scheme 3 Iminobenzoxazines: Intermediates Of the Total Synth...mentioning

confidence: 99%

Copper-catalyzed synthesis of heterocycles via oxidative ring closure reactions of aromatic nitriles with diaryliodonium salts

Aradi¹

2016

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Scheme 4. Recently, the microwave-assisted palladium-catalyzed synthesis of imino-1,3benzoxazines was reported by Batra 22 et al. They also utilized isonitriles as starting materials which were reacted with 2-bromophenylureas in the presence of Pd-ligand and cesium carbonate base.The first synthesis of imino-1,4-benzoxazines ( 27) was reported by Weidinger and Kranz 23 in 1964 by the condensation of ortho-aminophenols (25) with oxalyl bismethylimidate (26) under acidic conditions (Scheme 5). Scheme 5. Preparation of 2-imino-3-amino-1,4-benzoxazinesIn 2009, González 24 et al. developed a three-component synthesis for the construction of 2-imino-1,4-benzoxazine derivatives (31) from salicylaldehydes (28), ortho-aminophenols (29) and arylisocyanides (30) in toluene in the presence of ammonium-chloride (Scheme 6). The desired iminobenzoxazine derivatives could also be obtained by preparing the putative Schiff base intermediate followed by addition of the isonitrile, but in that case, more vigorous conditions were required.

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