Synthesis of erythronolide a via a very efficient macrolactonization under usual acylation conditions with the Yamaguchi reagent

Enantioselective total synthesis and structural assignment of callyspongiolide

“…Use of BOP-Cl 35 showed a modest improvement in reaction yield (entry 4). Alternatively, employing Yonemitsu’s variation 36 of the Yamaguchi macrolactonization was most effective, whereby instead of preforming the mixed anhydride, a solution of seco acid is added directly to the cocktail of reagents. In this manner, alkynyl lactone 27 was obtained in 67% yield over three steps (entry 5).…”

A concise enantioselective synthesis of marine macrolide-stagonolide E via organocatalysis

“…Yamaguchi cyclization conditions with variation in bases and solvents, it gave a marginally improved yield (30%). The best yield of the desired macrolactone 20 (65% isolated yield) was obtained using a modification of Yamaguchi's cyclization, 13 wherein the seco-acid 19 was slowly added to a stirred solution of DMAP, 2,4,6-trichlorobenzoyl chloride and triethylamine in dry toluene at room temperature. 2-Methyl-6-nitrobenzoic anhydride (MNBA) 14 was also found to be quite effective as an activating agent (62% yield).…”

“…Subsequent filtration (diethyl ether eluent) and washing the filtrate with water, brine, followed by drying over anhydrous Na 2 SO 4 , and removal of solvent under reduced pressure gave a crude product, which upon chromatographic separation with petroleum ether/ethyl acetate (19:1 v/v) gave aldehyde 10 as a colorless liquid. Yield: 9.7 g, 98% yield; IR (CHCl 3 , cm À1 ): 3065, 3030, 2987, 1725, 1520, 1105; 1 H NMR (200 MHz, CDCl 3 ): d 9.8 (s, 1H), 7.2-7.4 (m, 5H), 4.5 (s, 2H), 3.5 (t, 2H), 2.4 (t, 2H), 1.6 (m, 4H), 1.4 (m, 4H); 13 …”

“…Yield: 0.92 g, 88%; 1H), 4.13-4.24 (m, 3H), 4.56 (q, J = 14.5, 6.5 Hz, 2H), 5.68 (d, J = 11.5 Hz, 1H), 5.88 (dd, J = 8.0, 15.0 Hz, 1H), 6.55 (t, J = 11.5 Hz, 1H), 7.47 (dd, J = 11.5, 15.0 Hz, 1H);13 C NMR (CDCl 3 , 100 MHz): d 14.2, 23.7, 31.6, 34.7, 55.5, 59.9, 60.3, 67.8, 94.1, 118.2, 128.1, 142.1, 142.3, 166.6; Anal. calcd for C 15 H 24 O 6 : C, 59.98; H, 8.05; found: C, 59.97; H, 8.01.…”

Total Synthesis of Iejimalide B

“…In line with our previous experiences, [4] the intermolecular esterification of 14 and 33 could be effected under Yonemitsu conditions (Scheme 6). [24] We were delighted to see that the projected ring closure of the polyunsaturated compound 34 with the aid of the "second generation" ruthenium alkenylidene complex 35 [25] gave the desired macrocycle in almost quantitative yield as the required E isomer only.…”