Diazo Reagents in Copper(I)‐Catalyzed Olefination of Aldehydes

Abstract

The olefination of aldehydes to synthesize unsaturated ketones, esters, amides and phosphonates using diazo reagents and triphenylphosphine in the presence of copper(I) iodide as catalyst, is described. Good to excellent E:Z selectivities as well as yields were obtained for a large variety of aliphatic, aromatic and heteroaromatic aldehydes. The reaction showed also an excellent functional group compatibility and aldehydes were selectively reacted in the presence of ketone, nitro, amine, ether, acetal, thioether and halide groups. The use of a cost-effective copper salt as a catalyst is advantageous compared to previously reported expensive transition metal complexes. The method was used in the total synthesis of the scutifoliamide A, a biologically active compound that exhibits antifungal activity.

Contrasting Reactivity of 2-Mesityl-1,8-Naphthyridine (Mes-NP) with Singly-Bonded [RhII–RhII] and [RuI–RuI] Compounds

“…[48] Transition-metal catalyzed olefination of aldehydes with diazoacetate in the presence of triarylphosphine has emerged as an efficient method for the construction of C¼C double bonds. [49][50][51][52][53][54][55][56][57][58] Ruthenium and rhodium complexes are well known carbene-transfer catalysts from commercially available ethyl diazoacetate (EDA). Reaction of benzaldehyde (1 mmol), triphenylphosphine (Ph 3 P, 1.2 mmol), EDA (1.5 mmol) and catalytic amount of 2 (0.01 mmol) gave ethyl cinnamate in 68% conversion after 6 h (Table 3, entry 3).…”

Systematic Study on the Catalytic Arsa‐Wittig Reaction

“…( E , E )‐Ethyl‐5‐phenylpent‐2,4‐dienoate (17) : 2,6‐Dichlorobenzaldehyde (175 mg, 1.00 mmol), ethyl bromoacetate (201 mg, 1.20 mmol), Ph 3 SiH (313 mg, 1.20 mmol), diisopropylethylamine (155 mg, 1.20 mmol), and 1‐phenylarsolane ( 5 , 21 mg, 0.10 mmol) were used. Product: 164 mg, 0.809 mmol, 81 %.…”

Batch and Continuous‐Flow One‐Pot Processes using Amine Diazotization to Produce Silylated Diazo Reagents

“…[1,2] TMSCHN 2 has been used extensively in various reactions. [4,5] Thesynthesis of TMSCHN 2 by the diazo-transfer reaction of TMSCH 2 MgCl with diphenyl phosphoryl azide has been largely adopted because of the facile scalability of the process. [4,5] Thesynthesis of TMSCHN 2 by the diazo-transfer reaction of TMSCH 2 MgCl with diphenyl phosphoryl azide has been largely adopted because of the facile scalability of the process.…”

“…[2,3] Improved chemoselectivity relative to CH 2 N 2 is often observed because of the reactivity profile of the more hindered and less basic TMSCHN 2 .F or example,i nt he methylenation of aldehydes and ketones disclosed by our group,C H 2 N 2 proved to be unreactive, whereas high yields were obtained with TMSCHN 2 . [4,5] Thesynthesis of TMSCHN 2 by the diazo-transfer reaction of TMSCH 2 MgCl with diphenyl phosphoryl azide has been largely adopted because of the facile scalability of the process. [6] Despite these advantages,afew drawbacks remain, including long reaction times (> 20 h), as well as the tedious distillation of ether from TMSCHN 2 .C ontinuousflow processes [7] have been developed to safely prepare diazo reagents and mitigate some of these challenges.…”