Rhodium-catalyzed regio- and stereoselective oxyamination of dienes via tandem aziridination/ring-opening of dienyl carbamates

Abstract

The reaction of dienyl carbamates with PhI(OR)2 in the presence of rhodium catalysts affords vinyl aziridines which are in situ regio- and stereoselectively opened to afford oxyamination products resulting from a selective S(N)2 (Rh2(OAc)4/PhI(OPiv)2) or S(N)2' (Rh2(OPiv)4/PhI(OAc)2) opening. The scope and limitations of this tandem process are described.

Enantioselective Synthesis of Aminodiols by Sequential Rhodium‐Catalysed Oxyamination/Kinetic Resolution: Expanding the Substrate Scope of Amidine‐Based Catalysis

“…Derivatives (±)‐ 2 a – 4 a , with Bz, Ac and Piv protecting groups, were synthesised from carbamate 1 , Rh 2 (OAc) 4 catalyst and the appropriate PhI(OR) 2 reagent under the optimised reaction conditions for S N 2 aziridine opening. In this case, catalyst and base play a determining role in the efficiency and selectivity (S N 2 versus S N 2′) of the oxyamination reaction . Alternatively, PhIO‐mediated intramolecular aziridination of carbamate 1 was applied for the preparation of compounds (±)‐ 5 and (±)‐ 6 , with a mixture of water in acetonitrile or methanol, respectively, as nucleophiles for the ring‐opening step.…”

“…In 2001, Donohoe and co‐workers reported the oxyamination of 2,4‐dien‐1‐yl carbamates with osmium reagents to afford 2‐aminopent‐4‐en‐1,3‐diol derivatives (Scheme a) . Recently, we demonstrated that rhodium‐catalysed intramolecular aziridination of dienyl carbamates in the presence of PhI(OR) 2 afforded vinylaziridines, which were opened in situ by the OR group released after formation of the nitrene transfer reagent. The regioselectivity of this process (S N 2 versus S N 2′) was controlled by properly selecting the catalyst and PhI(OR) 2 reagent (Scheme b) .…”

“…Recently, we demonstrated that rhodium‐catalysed intramolecular aziridination of dienyl carbamates in the presence of PhI(OR) 2 afforded vinylaziridines, which were opened in situ by the OR group released after formation of the nitrene transfer reagent. The regioselectivity of this process (S N 2 versus S N 2′) was controlled by properly selecting the catalyst and PhI(OR) 2 reagent (Scheme b) . Thus, oxazolidinone derivatives with opposite relative configuration can be obtained from the same carbamate, depending on whether an osmium or rhodium catalyst is used (Scheme ), or by modifying the configuration of the proximal double bond at the dienyl carbamate under a given catalytic system.…”

Glycal Metallanitrenes for 2-Amino Sugar Synthesis: Amidoglycosylation of Gulal-, Allal-, Glucal-, and Galactal 3-Carbamates

“…Addition of the metallanitrene to the glycal π bond provides a glycosyl aziridine (e.g., 8 in the 3- β series), possibly with the metal still complexed at nitrogen (not shown). 50 As long as the N−anomeric contact is present, the acceptor adds in S N 2 fashion, leading to the 1,2-trans amidoglycosylation ( AG ) product. Dihydropyranone ( DHP ) byproduct formation, meanwhile, also originates from the metallanitrene intermediate 7 , as supported by our previous studies that utilized an alternative N -tosyloxycarbamate nitrene precursor (which obviates the need for a hypervalent iodine oxidant) and gave the same distribution of amidoglycosylation and C3−H oxidation products with rhodium catalysis as compared to the standard primary carbamate using PhIO.…”

Copper-Catalyzed 1,2-Amino Oxygenation of 1,3-Dienes: A Chemo-, Regio-, and Site-Selective Three-Component Reaction with O-Acylhydroxylamines and Carboxylic Acids

“…7 In another example, rhodium-catalyzed amino oxygenation was achieved with chemo- and site-selectivity through a diene-tethered nitrogen group yet gave a nearly equal mixture of 1,2- and 1,4-addition products. 8 Despite these seminal developments, a three-component modular and selective amino oxygenation reaction incorporating a diverse range of 1,3-dienes remains lacking, and is greatly desired. 9…”