GaCl₃-Catalyzed Insertion of Isocyanides into a C−O Bond in Cyclic Ketals and Acetals

Abstract

The reaction of cyclic ketals or acetals with 2,6-dibromophenylisocyanide in the presence of a catalytic amount of GaCl(3) results in the insertion of isocyanide into the carbon-oxygen bond of cyclic ketals and acetals. [reaction: see text]

Recent applications of gallium and gallium halides as reagents in organic synthesis

“…5 In a related study, Chatani et al demonstrated the GaCl 3 -catalysed insertion reaction of isocyanides into the carbon-oxygen bond of cyclic ketals and acetals, affording iminolactone derivatives (Scheme 35). 80 Over the course of the work, it was discovered that increasing the steric demand of the isocyanide had little effect on the efficiency of 10 the reaction. However, electron withdrawing atoms such as chlorine and bromine on the phenyl ring of the aryl isocyanide led to a marked improvement in both yield and selectivity for the monoinsertion product.…”

Direct Passerini Reaction of Aldehydes, Isocyanides, and Aliphatic Alcohols Catalyzed by Bismuth (III) Triflate

“…On the other hand, Chatani and co-workers (Tobisu, M. et. al 2007, Yoshioka, S. at. al 2005 reported that the reaction of benzaldehyde, isocyanide, and silyl-protected aliphatic alcohol can be catalyzed by triflic acid to give α-alkoxy amides in moderate yield.…”

Renaissance of Organic Synthesis Using Isocyanides

“…As expected, the reaction proceeded to furnish the insertion product in an excellent yield (eq 5). 18 The use of aryl isocyanides bearing electron-withdrawing groups, such as Cl and Br, was essential for an efficient reaction. As shown in Table 1, acetals derived from aliphatic ketones gave rise to the corresponding insertion products in good yields (Entries 1 and 2).…”