An Efficient Synthesis of Antibiotic (−)-A26771B

The Berkeleylactones, Antibiotic Macrolides from Fungal Coculture

“…23,24 There have been several total syntheses published for A26771B that have shown that the configurations at C-5 and C-15 are consistent with berkeleylactones A and B. 25 We have reported the 1 H and 13 C NMR spectral data of 5 (Tables 2 and 4) to facilitate direct comparison to those of the berkeleylactones.…”

“…colorless oil, [ α ] 25 D −0.9 ( c 0.0300, CHCl 3 ); UV (MeOH) λ max (log ε ) 224 (3.5) nm; IR (CHCl 3 ) ν max 3416, 2928, 1744, 1702, 1288, 1163, 1043 cm −1 ; 1 H NMR see Table 2; 13 C NMR see Table 4; HRESIMS m / z [M − H] − 397.1846 (calcd for C 20 H 29 O 8 , 397.1862).…”

Stereoselective Total Synthesis of Mangiferaelactone using D‐Mannose as a Chiral Pool

“…After10min, the mixture was warmed to r.t.,and then a freshly preparedaq. Theresulting mixturewas heated to reflux for 6h.After completionofthe reaction,the solvent was evaporated, and the crude residue was purifiedb yC Ct oa fford pure product 15 as ac olorless oil ( [ 17]. of KOH(40 ml)inEtOH (20 ml, 20 gKOH dissolved in 40 ml dist.…”

“…Under Steglich conditions(DCC/ DMAP), the coupling of alcohol 5 with acid 4 gave the corresponding ester 3 in 85% yield [ 15]. Removal of the TBS ether using pyridine ·HFf ollowed by ar ing-closing metathesis of 3 using Grubbss econd generation catalyst [16] the macrolide 15 with succinic anhydride (75% yield) [17]followed by the removal of acetonide using CeCl 3 ·7 H 2 Ou nder reflux conditions [ 18]f urnished the desired molecule, mangiferaelactone (1)i n7 3% yield. Thes pectroscopic data ( 1 H-and 13 C-NMR, IR, [a] 25 D )o fm angiferaelactone (1)w ere identical in all respects with the data reported in the literature [6](Scheme4).…”

Metátese de olefinas aplicada ao fechamento de anéis: uma ferramenta poderosa para a síntese de macrociclos naturais

“…Neste trabalho, o uso de catalisador de Grubbs-I 3 conduziu à macrociclização do dieno terminal 80 em bom rendimento e excelente estereosseletividade, não sendo observada reação competitiva com a ligação dupla C2-C3, devido à baixa afinidade do catalisador com esta ligação deficiente em elétrons. A redução seletiva da ligação dupla C9-C10 de 81 produziu o intermediário 82, cuja transformação em 83 estava já descrita na literatura 71 .…”