Samarium diiodide/hexamethylphosphoramide

Figure 4.11. Examples of redox-initiated radical reactions. Samarium diiodide reduction of the bromide gives a radical that cyclizes faster than the second reduction reaction. Manganese triacetate oxidation of the P-keto ester gives an enol radical that is not further oxidized by the manganese reagent. The IBX oxidizes anilides to the corresponding radicals. Hexamethylphosphoramide = HMPA and Tetrahydrofuran = THE.

N-Acylated indoles are converted into tricyclic compounds 211 in the presence of samarium diiodide (2.5 eq.) along with hexamethylphosphoramide (10 eq.) and phenol (2.0 eq.) as proton source <20030L4305>. 

N-Acylated indoles 1520 furnished tricyclic compounds 1521 in the presence of samarium diiodide (2.5 equiv) in tetrahydrofuran along with an excess of hexamethylphosphoramide (10 equiv) and phenol (2 equiv) as proton source (Equation 311) <20030L4305>. Whereas methyl ketone 1520 (R = Me) smoothly cyclized to compound 1521 (in 73% yield), the corresponding aldehyde 1520 (R = H) provided compound 1521 only in low yield (28%). 

Samarium diiodide j hexamethylphosphoramide Phosphines from phosphine oxides Distannanes from distannoxanes s. 44, 993 SmI KMe-,N),PO 5PO - ( Sn)20 SnSn ... 

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