4 research outputs found
Diiodoindium(III) Cation, InI<sub>2</sub><sup>+</sup>, a Potent Yneophile. Generation and Application to Cationic Cyclization by Selective π‑Activation of CC
The removal of the iodide ion from
indium triiodide by means of
reactive AgÂ(I) salts leads to the formation of the highly reactive
ligandless cation InI<sub>2</sub><sup>+</sup>, which is unusual in
having two vacant low-lying p-orbitals. This bivalent Lewis acidity
leads to an especially high affinity for the two orthogonal π-bonds
of carbon–carbon triple bonds. Consequently, the double-coordinating
InI<sub>2</sub><sup>+</sup> is an especially effective reagent for
the selective activation of Cî—¼C and the catalytic initiation
of cationic cyclization processes. A number of such reactions are
described to demonstrate synthetic utility
Reversal of the Importance of Steric and Electronic Effects in the Base-Promoted α‑Silylation of Sulfides
Lithiation
of α–C-H groups in organic substrates by
RLi or R<sub>2</sub>NLi followed by silylation with R′<sub>3</sub>SiCl generally provides analogous products regardless of the
R′ group of R′<sub>3</sub>SiCl. A striking exception
using 3,4-benzothiophane as substrate depending on whether R′
is methyl, phenyl, or isopropyl is demonstrated. With R′ =
Me or Ph, the geminal α,α-bis-silylated products result
whereas with <i>i</i>-Pr<sub>3</sub>SiCl the <i>trans</i>-α,α′-bis-silylated sulfide is formed. The latter
pathway provides ready access to the <i>C</i><sub>2</sub>-symmetric enantiomers of <i>trans</i>-2,5-bisÂ(triisopropylsilyl)-3,4-benzothiophane
Selective Formation of Six-Membered Oxa- and Carbocycles by the In(III)-Activated Ring Closure of Acetylenic Substrates
Fifteen examples are disclosed of efficient In(III)-catalyzed six-membered ring closure leading to bi-, tri-, and tetracyclic products