N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• , including both aromatic and saturated NH-substrates. This yields structures that are appealing for generating cereblon ubiquitin-ligase ligands and for potential use in crafting PROTAC molecules. Keywords: CRBN ligands; diazocarbonyl compounds; N–H insertion reaction; N-heterocycles; Rh(II)-catalysis

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• method for the preparation of this class of compounds [2] and showed that DAS can undergo Rh(II)-catalyzed insertion reactions into the heteroatom–H bonds [3]. In 2020, it was shown that under Rh(II) catalysis, DAS can enter insertion reactions into the C–O bond of ethers [4], a rare transformation for

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• expansion [12], and C–H insertion and Si–H insertion reactions [13]. Under Rh(II)-catalysis conditions, 2b extrudes N2 much faster than 1 (15 s vs 8 min to 50% conversion) [14]. The higher reaction rate implies a lower turnover limiting barrier in the catalytic cycle with 2b compared to 1. This example made

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• , Universitetskaya nab. 7–9, 199034 St. Petersburg, Russia 10.3762/bjoc.11.35 Abstract Strained azirinium ylides derived from 2H-azirines and α-diazoketones under Rh(II)-catalysis can undergo either irreversible ring opening across the N–C2 bond to 2-azabuta-1,3-dienes that further cyclize to 2H-1,4-oxazines or

• reversibly undergo a 1,5-cyclization to dihydroazireno[2,1-b]oxazoles. Dihydroazireno[2,1-b]oxazoles derived from 3-aryl-2H-azirines and 3-diazoacetylacetone or ethyl diazoacetoacetate are able to cycloadd to acetyl(methyl)ketene generated from 3-diazoacetylacetone under Rh(II) catalysis to give 4,6-dioxa-1

• active electrophilic trap in the reaction mixture. 3-Diazoacetylacetone under Rh(II)-catalysis gives, along with a Rh(II) carbenoid, a highly electrophilic acetyl(methyl)ketene (12) via Wolff rearrangement (Scheme 3). The nucleophilic attack of the azirenooxazole 10j nitrogen on the ketene sp-carbon