Rhodium-catalyzed diastereoselective synthesis of highly substituted morpholines from nitrogen-tethered allenols

Abstract

Rhodium-catalyzed intramolecular cyclization of nitrogen-tethered allenols was investigated for the synthesis of functionalized morpholines. By using this strategy, various N-protected 2,5- and 2,6-disubstituted as well as 2,3,5- and 2,5,6-trisubstituted morpholines...

Enantioselective Synthesis of Allylic Sulfones via Rhodium-Catalyzed Direct Hydrosulfonylation of Allenes and Alkynes

“…Notably, the highly strained cyclopropane ring in 3i was also tolerated under the mild optimized conditions without any discernible transition-metal-catalyzed ring-opening byproducts . Reactions of allenes with unprotected alcohol and mono-Ts-protected amine furnished the desired hydrosulfonylation products ( 3j and 3k ) with excellent ee, and no intramolecular cyclized product was detected . To construct a fully substituted stereogenic center, geminally disubstituted allene was tested; unfortunately, it failed to deliver the product ( 3l ) in satisfactory yield and ee.…”