Rhodium-Catalyzed Transannulation of N-Sulfonyl-1,2,3-triazoles and Epoxides: Regioselective Synthesis of Substituted 3,4-Dihydro-2H-1,4-oxazines

Abstract

Rhodium-catalyzed transannulation of 1,2,3-triazoles and ring-opening reactions of epoxides is described. A number of 3,4-dihydro-2H-1,4-oxazines are obtained in moderate yields probably involving generation of α-imino rhodium(II) carbene species.

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2014

“…A mechanistically similar approach to the synthesis of related oxygen and sulfur heterocycles was also reported [1100]. Dihydro-1,4-oxazines were prepared through rhodium-catalyzed reaction of sulfonated triazoles with epoxides [1101]. Synthesis of seven-membered ring amines was accomplished through the rhodium-catalyzed intramolecular reaction of sulfonated triazoles with conjugated dienes in a process that involves…”

Metal‐Catalyzed Cyclization: Synthesis of (Benzo)morpholines and (Benzo)[1,4]dihydrooxazines

“…Wang, Chen et al adopted a different strategy for the construction of dihydroxazines, using 1,2,3‐triazoles 160 and styrene oxides 159 as partners and a Rh‐catalyst (Scheme ) …”

Recent Advances in the Synthesis of Heterocycles and Related Substances Based on α‐Imino Rhodium Carbene Complexes Derived from N‐Sulfonyl‐1,2,3‐triazoles

“…[34] [Rh 2 (S-NTTL) 4 ]o r [Rh 2 (S-PTV) 4 ]w as used depending on different substrates. [34] [Rh 2 (S-NTTL) 4 ]o r [Rh 2 (S-PTV) 4 ]w as used depending on different substrates.…”

“…Chen and co-workersf ound that epoxides 112 could react with N-sulfonyl-1,2,3-triazoles 1 to give 3,4-dihydro-2H-1,4-oxazines 113 in moderate yield (Scheme 23). [34] [Rh 2 (S-NTTL) 4 ]o r [Rh 2 (S-PTV) 4 ]w as used depending on different substrates. The proposed mechanism involves the epoxides 112 reacting with the electrophilic rhodium(II)c arbenoid to generate oxonium species 114,w hich then undergoes CÀOb ond cleavage to give the carbocationic intermediate 115.R ing closure then takes place to afford the final product.…”

“…Chen and co‐workers found that epoxides 112 could react with N ‐sulfonyl‐1,2,3‐triazoles 1 to give 3,4‐dihydro‐2 H ‐1,4‐oxazines 113 in moderate yield (Scheme ) . [Rh 2 ( S ‐NTTL) 4 ] or [Rh 2 ( S ‐PTV) 4 ] was used depending on different substrates.…”