“…This reaction has been used in a number of 11- to 16-membered macrolactones, ,,− in the total syntheses of natural products such as (+)-amphidinolide K (eq a in Scheme ), 19-epi-avermectin B 1 , (+)-brefeldin C, citreofuran, antibiotics derived from erythromycin, , (+)-gloeosporone, − hypothemycin, cyclothialidine, lasiodiplodin, lobotamide C, ,, latrunculins A and B, − laulimalide, − where Yamaguchi and Keck methodologies result in Z / E isomerization of the conjugated double bond (eq b in Scheme ), leucascandrolide A, − (+)-milbemycin β 3 , , (+)-patulolide, suspensolide, , diolides UK-2A and UK-3A, , verrucarin A, zearalane, and aplyronine A analogues, in the total synthesis of griseoviridin, and in several approaches to its thiolactone core, − where, in particular, a highly strained nine-membered lactone has been obtained by Pancrazi 588 (see eq c in Scheme ). This methodology has also been successfully used in the syntheses of various cyclodepsipeptides as illustrated in Scheme . ,,− 69 …”
Section: Macrolactonizations By “Alcohol” Activationmentioning
confidence: 99%
“…This reaction has been used in a number of 11-to 16membered macrolactones, 186,225,[551][552][553][554] in the total syntheses of natural products such as (+)-amphidinolide K 555 (eq a in Scheme 69), 19-epi-avermectin B 1 , 556 (+)-brefeldin C, 557 citreofuran, 558 antibiotics derived from erythromycin, 559,560 (+)-gloeosporone, [561][562][563] hypothemycin, 564 cyclothialidine, 565 lasiodiplodin, 123 lobotamide C, 70,513,566 latrunculins A and B, [567][568][569][570][571] laulimalide, [572][573][574] where Yamaguchi and Keck methodologies result in Z/E isomerization of the conjugated double bond (eq b in Scheme 69), leucascandrolide A, [575][576][577] (+)-milbemycin β 3 , 578,579 (+)-patulolide, 580 suspensolide, 581,582 diolides UK-2A and UK-3A, 583,584 verrucarin A, 585 zearalane, 586 and aplyronine A analogues, 361 in the total synthesis of griseoviridin, 587 and in several approach...…”
“…This reaction has been used in a number of 11- to 16-membered macrolactones, ,,− in the total syntheses of natural products such as (+)-amphidinolide K (eq a in Scheme ), 19-epi-avermectin B 1 , (+)-brefeldin C, citreofuran, antibiotics derived from erythromycin, , (+)-gloeosporone, − hypothemycin, cyclothialidine, lasiodiplodin, lobotamide C, ,, latrunculins A and B, − laulimalide, − where Yamaguchi and Keck methodologies result in Z / E isomerization of the conjugated double bond (eq b in Scheme ), leucascandrolide A, − (+)-milbemycin β 3 , , (+)-patulolide, suspensolide, , diolides UK-2A and UK-3A, , verrucarin A, zearalane, and aplyronine A analogues, in the total synthesis of griseoviridin, and in several approaches to its thiolactone core, − where, in particular, a highly strained nine-membered lactone has been obtained by Pancrazi 588 (see eq c in Scheme ). This methodology has also been successfully used in the syntheses of various cyclodepsipeptides as illustrated in Scheme . ,,− 69 …”
Section: Macrolactonizations By “Alcohol” Activationmentioning
confidence: 99%
“…This reaction has been used in a number of 11-to 16membered macrolactones, 186,225,[551][552][553][554] in the total syntheses of natural products such as (+)-amphidinolide K 555 (eq a in Scheme 69), 19-epi-avermectin B 1 , 556 (+)-brefeldin C, 557 citreofuran, 558 antibiotics derived from erythromycin, 559,560 (+)-gloeosporone, [561][562][563] hypothemycin, 564 cyclothialidine, 565 lasiodiplodin, 123 lobotamide C, 70,513,566 latrunculins A and B, [567][568][569][570][571] laulimalide, [572][573][574] where Yamaguchi and Keck methodologies result in Z/E isomerization of the conjugated double bond (eq b in Scheme 69), leucascandrolide A, [575][576][577] (+)-milbemycin β 3 , 578,579 (+)-patulolide, 580 suspensolide, 581,582 diolides UK-2A and UK-3A, 583,584 verrucarin A, 585 zearalane, 586 and aplyronine A analogues, 361 in the total synthesis of griseoviridin, 587 and in several approach...…”
“…These metabolites were reported to have phototoxic, ,, cytotoxic, antifungal, ,,, antibacterial, , and antiviral activities . The flexible ring system and the remarkable bioactivities of these metabolites have attracted great interest as targets for total synthesis. − In particular, a number of total syntheses of recifeiolide, − cladospolides, − and patulolides − have been reported.…”
Dendrodolides A-M (1-13), 13 new 12-membered macrolides, were isolated from Dendrodochium sp., a fungus associated with the sea cucumber Holothuria nobilis Selenka, which was collected from the South China Sea. The structures of the dendrodolides were elucidated by means of detailed spectroscopic analysis and X-ray single-crystal diffraction. The absolute configurations were assigned using the modified Mosher method, exciton-coupled circular dichroism (ECCD), electronic solution and solid-state circular dichroism (ECD) supported by time-dependent density functional theory (TDDFT) ECD calculations, and X-ray analysis. A detailed conformational analysis of the 13 derivatives indicated that the conformation of the flexible macrolide ring plays a decisive role in their chiroptical properties. Thus, it is highly recommended to apply advanced levels of theory and to avoid simple comparison of ECD spectra to determine the absolute configurations of these derivatives. In an in vitro bioassay, compounds 1-5, 7-9, 11, and 12 exhibited different levels of growth inhibitory activity against SMMC-7721 and HCT116 cells. This is the first report of 12-membered macrolides from the fungus of the genus Dendrodochium . The coisolation of four pairs of epimers is extremely interesting and indicates the complexity of β-ketoreductase stereospecificity in the biosynthesis of enigmatic iterative fungal polyketides.
“…Exhibiting both antifungal and antibacterial activities, the patulolides have been the targets of several total syntheses. Some strategies for macrocycle formation include utilizing the Yamaguchi macrolactonization, ,,− Mitsunobu lactonization, Shiina lactonization, or ring-closing metathesis . The olefin has been constructed by various methods including Horner–Wadsworth–Emmons and Wittig olefinations , and a photochemical rearrangement of an epoxydiazomethyl ketone .…”
Four different Rh-catalyzed asymmetric hydroformylation (AHF) tandem reactions have been developed in the context of the total syntheses of (+)-patulolide C, (-)-pyrenophorol, (+)-decarestrictine L, and (+)-Prelog-Djerassi lactone. A total synthesis of (+)-patulolide C has been accomplished in three steps utilizing a Rh(I)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of a known alkyne to give a Z-enol acetate with excellent selectivity. An AHF/intramolecular Wittig olefination cascade was utilized to set the C4-hydroxyl stereochemistry, E-olefin geometry, and form the macrolactone. In addition, both (-)-pyrenophorol and (+)-decarestrictine L have been synthesized from the enantiomeric (4R)- and (4S)-4-(tert-butyldimethylsiloxy)-1-pentyne in five and four steps, respectively. These syntheses feature Ru(II)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of terminal alkynes followed by AHF/Wittig olefination sequences to rapidly establish functionality and stereogenicity. A synthesis of (+)-Prelog-Djerassi lactone was accomplished in three isolations from the known 1-vinyl-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane ortho ester. An AHF/crotylation tandem sequence has been developed to set the C2-C4 stereochemistry. An asymmetric hydrogenation was employed to set the C6 stereochemistry, resulting in an especially efficient enantioselective synthesis from achiral starting material. In summary, these syntheses have greatly improved efficiency in terms of atom-economy, catalytic stereoselective transformations, inexpensive reagents, step-counts, and overall yield when compared with previous synthetic attempts.
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