Transformation of gem‐Dicyanoethenes by Samarium: Direct Formation of Indenes or Direct Decyanation with in Situ Disilylation

Abstract

Intramolecular cyclization of 1,1‐diaryl‐2,2‐dicyanoethenes promoted by samarium metal in DMF in the presence of TMSCl allowed direct construction of the indene core, whereas 1‐alkyl‐1‐aryl‐2,2‐dicyanoethenes underwent intermolecular coupling cyclization and decyanation under the same conditions. Simultaneously, disilylation occurred at the amino moiety resulting from the reduction of the cyano group. However, only simple reduction of the C=C bonds is observed when a trace amount of water presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Organic Synthesis with Elemental Lanthanides – Going Beyond Samarium and Ytterbium

“…On the other hand, aryl alkyl substituted gem-dicyanoethenes 74 led to dicyano substituted cyclopentenes 75 bearing again a disilylated amino group (Scheme 16). [35] The use of lanthanides in catalytic amounts has been rarely described. In 2009, it was shown that Sm metal catalyzed the Sonogashira coupling of aryl iodides 76 and alkynes 77 (Scheme 17a).…”

“…Transformation of gem-dicyanoethenes by Sm in DMF. [35] Scheme 17. Sm metal catalyzed (a) Sonogashira coupling and (b) cyanation of arylhalides.…”

“…On the other hand, aryl alkyl substituted gem‐dicyanoethenes 74 led to dicyano substituted cyclopentenes 75 bearing again a disilylated amino group (Scheme 16). [35] …”

“…[34] Two different reaction outcomes were observed in the reaction of Sm metal with gem-dicyanoethenes in DMF in the presence of trimethylsilyl chloride (Scheme 16). [35] For diaryl substituted substrates 72, the formation of indene derivatives 73 was obtained. In the course of this reaction one cyano group was reduced and disilylated at the nitrogen atom.…”

The reductive decyanation reaction: an overview and recent developments

“…Kang et al reported the decyanation of both malononitriles and α-cyanoesters using samarium(II) iodide/THF/HMPA at respectively 0 °C and room temperature [ 123 ]. Metallic samarium can also promote the decyanation [ 124 ].…”