Synthesis of 2‐Substituted 2‐Amino Ketones by Rhodium‐Catalyzed Reaction of N‐Sulfonyl‐1,2,3‐triazoles with 2‐Alkenols

Abstract

A study on a rhodium(II)‐catalyzed reaction of N‐sulfonyl‐1,2,3‐triazoles with 2‐alkenols is reported. The reaction is initiated by insertion of an α‐imino carbene into the O–H linkage of alcohol, forming a 2‐alkenoxy enamide intermediate. A thermal [3,3]‐sigmatropic rearrangement follows to yield 2‐substituted 2‐amino ketone in a stereoselective manner. The successful application of this methodology to a formal synthesis of (–)‐α‐conhydrine is also described.

1,2,3-Triazole and Its Analogues: New Surrogates for Diazo Compounds

“…The synthetic utility of the α-allyl-α-amino ketones was explored by the synthesis of 3,4-dehydropiperidines. Importantly, (−)-α-conhydrine was synthesized in nine steps starting from the alkyne using this protocol …”

Recent advances in the synthesis of α-amino ketones

“…In addition, (S)-1-methyl-2-propen-1-ol (159) (97% ee) was used providing the expected product (160) in 93% yield with good chirality transfer (91% ee); this approach was later applied to the enantioselective synthesis of (−)-α-conhydrine. 94 Lee also exploited this chemistry to form α-substituted α-amino ketones with a view to forming γ-oxoβ-amino acids and δ-oxo-γ-amino acids. 95,96 Further building on this approach, Bi investigated the 1,2aminohydroxylation with a concomitant [1,3]-sigmatropic shift.…”

The Expanding Utility of Rhodium‐Iminocarbenes: Recent Advances in the Synthesis of Natural Products and Related Scaffolds

“…Murakami and co‐workers demonstrated an efficient synthesis of α‐allyl‐α‐amino ketones by utilizing N ‐sulfonyl‐1,2,3‐triazoles and allyl alcohols in the presence of a rhodium catalyst . It was proposed that this transformation proceeded via the O−H insertion reaction of the in situ generated rhodium carbenoid species into the O−H linkage and subsequent Claisen‐like [3,3]‐ sigmatropic rearrangement (Scheme ).…”

“…Murakami and co-workers demonstrated an efficient synthesis of a-allyl-a-aminok etones by utilizing N-sulfonyl-1,2,3-triazoles and allyl alcohols in the presence of ar hodiumc atalyst. [21] It was proposed that this transformation proceeded via the OÀH insertionr eaction of the in situ generated rhodiumc arbenoid (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010). In 2010, he moved to LanzhouU niversity (2010)(2011)(2012)(2013)(2014)(2015).…”