The ruthenium-catalyzed reduction and reductive N-alkylation of secondary amides with hydrosilanes: Practical synthesis of secondary and tertiary amines by judicious choice of hydrosilanes

Shiori Hanada, Toshiki Ishida, Yukihiro Motoyama, Hideo Nagashima

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113 Citations (Scopus)

Abstract

(Chemical Equation Presented) A triruthenium cluster, (μ3, η235-acenaphthylene)Ru 3(CO)7 (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1,1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (1 mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product. The product contaminated with only minimal amounts of ruthenium and silicon residues. On the basis of the products and observed side products as well as NMR studies a mechanistic scenario for the reaction is also described.

Original languageEnglish
Pages (from-to)7551-7559
Number of pages9
JournalJournal of Organic Chemistry
Volume72
Issue number20
DOIs
Publication statusPublished - Sep 28 2007

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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