Iron(II)‐catalyzed Oxidative Coupling of Vicinal Diols and 2‐Amino‐1,4‐naphthoquinone for the Synthesis of Pyrrolonaphthoquinones and Furanonaphthoquinones

Abstract

Direct oxidative coupling of vicinal diols with 2aminonaphthoquinones has been studied for the selective synthesis of benzo[f]indole-4,9-diones at a moderate temperature. In the presence of an environmentally benign iron catalyst, the vicinal diols were oxidized to α-hydroxy carbonyl compounds. Subsequently, 2-amino naphthoquinone reacted with the resultant α-hydroxy carbonyl compound through tandem NÀ C and CÀ C bond formation to afford a vast range of pyrrolonaphthoquinones in remarkable yield. Interestingly, when the 1,2-propanediol was used, the secondary alcohol group was oxidized preferably by resulting in the 2-methyl pyrrolonaphthoquinones as the major regioisomer. The synthetic utility of the current strategy was extended for onestep delivery of natural products, such as 3-methyl-1H-benzo [f]indole-4,9-dione (a secondary metabolite isolated from Goniothalamus tapis Miq. with anti-PAF activity), antibiotic utahmycin B (3-methyl-1H-benzo[f]indole-4,9-dione), cytotoxic avicequinone B and anti-viral FNQ3 (2-methyl-naphtho-[2,3-b]furan-4,9-dione).

Blue Light Irradiated Metal-, Oxidant-, and Base-Free Cross-Dehydrogenative Coupling of C(sp2)–H and N–H Bonds: Amination of Naphthoquinones with Amines

“…Furthermore, the synthesized C2-aminated naphthoquinones ( 1 – 15 , 18 – 27 , 43 – 47 ) could be utilized for the late-stage transformations, as several viable and practical synthetic routes have been reported for the transformation of synthesized C2-aminated naphthoquinones (Scheme ). − …”

Copper(I)-Mediated Divergent Synthesis of Pyrroquinone Derivatives and 2-Halo-3-amino-1,4-quinones

“…Broggini’s group developed a method for synthesis of pyrroquinones through the process of Rh­(II)-catalyzed ring opening of 4-(1,4- naphthoquinone)-substituted isoxazolin-5-ones, decarbonation, and electrocyclic and reductive elimination. Panda’s group developed an Fe­(II)-catalyzed directly oxidative tandem reaction of vicinal diols with 2-aminonaphtho­quinones to construct pyrronaphtho­quinones. Maurya et al reported Rh­(II)-catalyzed coupling of α-azidochalcones with 2-hydroxy-1,4-naphtho-quinone under blue LED light.…”

“…In previous work, 2-substituted naphthoquinones were usually used as one of the materials to construct pyrroquinone derivatives through tandem cyclization reactions − (Figure a). Representatively, Choudhury’s group reported an iodine-mediated three-component reaction of aryl methyl ketones or terminal aryl alkynes or arylglyoxal hydrate with barbituric acid and 2-aminonaphthoquinone for the synthesis of 2,3-disubstituted naphthoquinone-fused pyrroles.…”

“…Yield: 79%, 64 mg; red solid; mp 165−166 °C; R f = 0.43 (PE:EA = 5:1). 1 H NMR(400 MHz, δ 8.20(d, J = 7.7 Hz, 1H), 8.12 (d, J = 7.5 Hz, 1H), 7.77 (t, J = 7.5 Hz, 1H), 7.70 (t, J = 7.5 Hz, 1H), 7.65−7.53 (m, 2H), 7.31 (t, J = 7.7 Hz, 1H), 7.11 (t, J = 7.9 Hz, 2H).13 C{ 1 H} NMR(101 MHz, δ 179.5, 177.3, 144.0, 136.2, 135.0, 133.1, 132.7, 132.2, 129.9, 127 5,. 127.22, 127.19, 127.1, 127.0, 119.7, 108.8.…”

Ce-catalyzed regioselective synthesis of pyrazoles from 1,2-diols via tandem oxidation and C–C/C–N bond formation

“…8,9 With the availability of a great variety of synthetic methods, a few reports describe diols as attractive, eco-friendly, readily available and stable building blocks for the construction of regioisomerically pure pyrazoles (Scheme 1). 10 For example, Panda et al disclosed a seminal work on Fe( iii )-catalyzed regioselective synthesis of pyrazoles in the presence of an excess amount of diols. 10 a Later, they were able to synthesize substituted pyrazoles under neat conditions.…”