Highly Selective Syn Addition of 1,3‐Diones to Internal Ynamides Catalyzed by Zinc Iodide

Abstract

1,3‐Diones are already established as nucleophiles to perform additions to ynamides; the highly selective hydroalkoxylation of internal ynamides is now described. Several catalytic systems have been compared to perform this transformation, including transition‐metal‐based catalysts and Lewis acids. ZnI2 was found to be both very active and highly selective providing only E adducts through a syn addition. Investigation of the scope and limitations showed that this catalyst was compatible with various functional groups. In addition to seventeen examples of ynamide hydroalkoxylation, one example of ynamide hydroarylation is reported.

Reductions of Imines Using Zirconocene Chloride Hydride

“…13 C NMR (151 MHz, CDCl 3 ): δ = 149.9, 146.0, 135.4, 128.8, 128.8, 128.3, 128.2, 127.9, 124.3, 47.4 ppm. Spectral data are consistent with those in the literature . MS (APCI, m/z ): calcd.…”

Catalytic intermolecular hydrofunctionalizations of ynamides

“…Later, the same group showed that when the Lewis acid ZnI 2 was employed as the catalyst, hydroalkoxylation of internal ynamides with 1,3-diones could occur readily at room temperature and α-alkoxy enamides were afforded with high yields and selectivities (Scheme 39). 85 Aryl and alkyl-substituted ynamides were well tolerated in the process. Oxacyclic 1,3-dione was a suitable coupling partner as well.…”

Transition Metal‐Catalyzed Hydroalkoxylation of Alkynes: An Overview

“…ZnI 2 catalyzed intermolecular hydroalkoxylation of ynamides 6 with 1,3-diketones 7 was reported by Clavier and co-workers for the stereoselective synthesis of enol ethers 8 (Scheme 6). [14] The developed method offered access to various synthetically useful enol ethers in excellent yield and diastereoselectivity. The TIPS-alkynes (R 2 =TIPS, triisopropylsilyl) gave a trace amount Chemistry-A European Journal the major product along with aliphatic ketone as the minor product.…”