Direct, Catalytic Synthesis of Carbapenams via Cycloaddition/Rearrangement Cascade Reaction: Unexpected Acetylenes’ Structure Effect

Abstract

Reactions of acetylenes derived from glyceraldehyde and propargyl aldehyde show remarkable reactivity in Kinugasa cycloaddition/rearrangement cascade process catalyzed by Cu(I) ion. Reactions proceed by formation of a rigid dinuclear copper(I) complex in which each copper ion is coordinated to one or both oxygen atoms in the acetylene molecule and to both triple bonds. It has been demonstrated that one oxygen atom can be replaced by the phenyl ring, which is able to coordinate the copper ion by the aromatic sextet. Kinugasa reactions that proceed in a high yield can also be performed in the presence of a catalytic amount of the copper salt to provide products in an acceptable yield without a decrease of diastereoselectivity.

Hollow Nanospheres Constructed by CoS2 Nanosheets with a Nitrogen‐Doped‐Carbon Coating for Energy‐Storage and Photocatalysis

“…We began our studies by investigating the reaction of C , N ‐diphenylnitrone ( 1a ) with 3,3‐diethoxy‐1‐propyne ( 2a ) as the model reaction (Table 1). As we have shown in previous reports,11c alkyne 2a can serve as an excellent nonaromatic substrate, providing shorter reaction times as compared with the more commonly employed phenylacetylene. The stereochemistry at C‐3 of the obtained β‐lactam 3a was assigned by comparing the 1 H NMR coupling constants of the 3‐H and 4‐H protons.…”

“…All solvents were degassed before reaction. Alkynes 2b 11c and 2d 17 were synthesized according to literature procedures, the other alkynes were commercially available. Nitrones 1b – f were synthesized according to a modification of the procedure of Merino et al,18 and nitrones 1a 13c and 1g 19 were synthesized according to literature procedures.…”

Towards Isocoumarin‐Fused Enediyne Systems through the Electrophilic Cyclization of Methyl o‐(Buta‐1,3‐diynyl)benzoates

“…[14a] and 3-methoxyprop-1-yne (8f) [34] were synthesized by known procedures without any modification. All reactions were carried out under Ar in flame-dried glassware.…”

Total Synthesis and Structural Elucidation of Two Unusual Non‐Methylene‐Interrupted Fatty Acids in Ovaries of the Limpet Cellana toreuma

“…The crude products were used for the further reactions without purification due to the volatility of product 37 [57]. and diisopropylethylamine (8.0 mL, 46.2 mmol, 1.3 eq.)…”