Facile synthesis of (−)-6-acetoxy-5-hexadecanolide by size-selective ring-closing/cross metathesis

Metathetic Synthesis of Common and Medium-Sized Lactones: The State of the Art

“…The same isomerization was not observed when HG2 was the catalyst [190]. These findings were explained by supposing that metathesis catalyst G2 could be turned by the prolonged warming into a ruthenium isomerization catalyst [191], probably through the conversion into a ruthenium hydride species.…”

Regioselective Tandem Ring Closing/Cross Metathesis of 1,5‐Hexadien‐3‐ol Derivatives: Application to the Total Synthesis of Rugulactone

“…While the work described in the present publication was in progress, Quinn and co-workers reported an efficient synthesis of a naturally occurring pyrone on the basis of, first, RCM of a substituted 3-O-(1,5-hexadienyl) 3-butenoate and, second, after addition of a chosen alkene, by cross metathesis on the lateral chain. [14] In that case, Hoveyda-Grubbs catalyst 5b was however required to prevent additional isomerization of the newly created internal double bond. Disappointingly, the tandem procedure was unsuccessful, leading mainly to a product resulting from cross metatheses between the lesssubstituted double bonds.…”

“…Otherwise, the reaction between the unsaturation fixed on the acid chain could take place more favorably with the vinyl group to form a 6-allylpyrone structure compared to the reaction involving the allyl rest leading to a 7-vinyl caprolactone. [14,16,17] Treatment of 13 with alcohol 14a in the presence of Grubbs type II catalyst 5 afforded dimer structure 18, ketone 19 [18] resulting from the isomerization of the terminal double bond [19] and further reketonization, and also 5064 Scheme 3. Retrosynthetic analyses for 3 and related 6-allyl hexenolides 12.…”

“…As recently pointed out by Quinn et al, the presence of a hydroxy group close to the double bond seems to be detrimental to the efficiency of the reaction. [14] The reactivity of 13 in the absence of any alkene partner was also investigated. In that case, new structure 20 was isolated, resulting from a cascade reaction involving two double ring closures and a cross metathesis.…”

Enantioselective synthesis of (-)-(5R,6S)-6-acetoxyhexadecan-5-olide via tandem α-aminooxylation-Henry reaction

“…Owing to the potential of (-)-(5R,6S)-6-acetoxy-5-hexadecanolide 1a in controlling mosquito populations, several enantioselective synthetic approaches for 1a and its unnatural isomer (+)-6-acetoxy-5-hexadecanolide 1b (Figure 1) have been disclosed in the literature. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] As part of our research program aimed at developing the asymmetric synthesis of bioactive natural compounds, [30][31][32][33][34][35][36][37] we turned our attention to developing a flexible and simple approach for the asymmetric synthesis of functionalized δ-lactones and its application to asymmetric synthesis of (-)-(5R,6S)-6-acetoxyhexadecan-5-olide 1a. Herein, we report a new enantioselective synthesis of (-)-(5R,6S)-6-acetoxyhexadecanolide 1a employing tandem α-aminooxylation-Henry reaction as the source of chirality.…”