Access to 1-amino-3,4-dihydroisoquinolines via palladium-catalyzed C-H bond aminoimidoylation reaction from functionalized isocyanides

General stereoretentive preparation of chiral secondary mixed alkylmagnesium reagents and their use for enantioselective electrophilic aminations

A general preparation of enantiomerically and diastereomerically enriched secondary alkylmagnesium reagents was reported as well as their use for performing highly stereoselective transition-metal free electrophilic aminations leading to α-chiral amines in up to 97% ee. Thus, the reaction of t-BuLi (2.2 equiv.) with a mixture of chiral secondary alkyl iodides and the commercially available magnesium reagent Me3SiCH2MgCl in a 2 : 1 mixture of pentane and diethyl ether at up to -50 °C provided optically enriched secondary mixed alkylmagnesium species of the type alkyl(Me)CHMgCH2SiMe3 with high retention of configuration (up to 99% ee). The resulting enantiomerically enriched dialkylmagnesium reagents were trapped with electrophiles such as non-enolizable ketones, aldehydes, acid chlorides, isocyanates, chlorophosphines and O-benzoyl hydroxylamines providing α-chiral tertiary alcohols, ketones, amides, phosphines and tertiary amines in up to 89% yield (over three reaction steps) and up to 99% ee.

Advances in palladium-catalysed imidoylative cyclization of functionalized isocyanides for the construction of N-heterocycles

Palladium-catalysed isocyanide insertion reactions have witnessed great progress in recent years. In particular, imidoylative cyclization of functionalized isocyanides was successfully developed by taking advantage of the adjustable substituents on the isocyano group, opening a new avenue to access a variety of nitrogen-containing heterocycles. In this review article, we summarize the advances of functionalized isocyanide insertion reactions and highlight the breakthroughs of enantioselective palladium catalysed imidoylation reactions by using this strategy. Additionally, copper-catalysed cyclization reactions of functionalized isocyanides are briefly discussed.

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.