The A rndt‐ E istert Synthesis

Abstract

The Arndt‐Eistert synthesis is a procedure for converting an acid to its next highest homolog or to a derivative of the homologous acid, and an ester and an amide. The synthesis, which is applicable to both, aliphatic and aromatic acids involves the following three operations; formation of the acid chloride; reaction of the acid chloride with diazomethane to yield a diazoketone; and rearrangement of the diazoketone in the presence of suitable reagents and a catalyst (colloidal silver, platinum, copper). An acid is formed in the presence of water, and ester is produced in an alcohol, and am amide results when ammonia or an amine is used.

Synthesis of Ketones and Esters from Heteroatom-Functionalized Alkenes by Cobalt-Mediated Hydrogen Atom Transfer

“…Trimethylsilylalkenes undergo a novel oxidative desilylation to the corresponding ketone derivatives, thereby establishing a useful and mild alternative to the Tamao–Fleming oxidation . When used in conjunction with the Ramirez alkenylation, the oxydehalogenation of gem- dihaloalkenes provides a useful alternative to the Arndt–Eistert homologation …”

Gold-Catalyzed Diastereoselective Formal Intermolecular [4 + 2 + 1] Cycloaddition of 1,3-Dien-8-yne with Diazo Ester

“…On the other hand, diazo esters are identified as a versatile C 1 unit in organic chemistry and widely utilized in metal-catalyzed carbene transfer reactions for the synthesis of 3-membered rings ([2 + 1] cycloaddition) or 5-membered heterocycles ([2 + 2 + 1] cycloaddition through carbonyl ylide intermediate) . In addition, it has been known that diazo ester could engage in homo- or heterocarbene coupling reaction using Rh­(I), Au­(I), or other transition metals .…”

Short Synthesis of the Antidiabetic Octaketide Ethyl 2-(2,3,4-Trimethoxy-6-octanoylphenyl)acetate

“…We therefore attempted a Rh-catalyzed ortho-acylation of the aromatic carboxylic acid 6, 12 which was treated with octanoic anhydride and [Rh(cod)Cl] 2 to afford keto acid 7. A four-step transformation of 7, involving an Arndt-Eistert one-carbon homologation, was carried out, 13 but the undesired product 8, containing a heptylidene moiety, was as formed during the generation of the acid chloride. For our second approach, we chose 3,4,5-trimethoxybenzaldehyde (9) as a starting material and we treated this with NBS to give the aryl bromide 10 in 92% yield.…”