Formal Total Syntheses of the (−)-Salicylihalamides A and B From d-Glucose and l-Rhamnose

Abstract

[reaction: see text] Two formal total syntheses of the (-)-salicylihalamides, based on chiral pool approaches, are reported. D-glucose and L-rhamnose were used to prepare advanced intermediates 23 and 54, which can be converted in three or four steps, respectively, to the target compounds. The synthesis of 23 from a known D-glucose-derivative was accomplished in 12 steps and 17% overall yield, and the synthesis of 54 from a known L-rhamnose-derivative was done in nine steps and 6% overall yield. A key step in the synthesis was a ring-closing metathesis reaction to prepare the macrocyclic ring system. It was demonstrated that the phenolic protecting group was critical for inducing the preferential formation of the desired E isomer. It was further shown that the protecting group at the C13 hydroxyl group had no significant influence on the E:Z ratio during the ring-closing metathesis reaction.

Transition metals in organic synthesis: Highlights for the year 2005

“…(179)) [937]. Selective conjugate reductions of electron-deficient alkenes using Stryker's reagent, [CuHPPh 3 ] 6 , was used in synthesis toward vannusal A [797], (−)-salicylhalamides A and B [938], trans-kumausyne [939], BCDE fragment of brevetoxin A [940], C26-C40 subunit of spirastrellolide [941] and a laulimalide analog [921]. A copper-catalyzed dynamic kinetic resolution of ␣,␤-unsaturated lactones via asymmetric conjugate reduction was used in a synthesis of eupomatilone-3 (Eq.…”

“…(221)) [1117,1118], hybrids of d-galactose with 1-deoxynojirimycin analogs [1119], the tetracyclic core of tetrapentalones [1120], 1-epi aglycon of cripowellins A and B [445], gambieric acid [1121], aspercyclide C [524], radicicol and pochonin C [1122], trachelanthamidine [1123], heliannuols G and H [652], (−)-Geismann-Waiss lactone [1124], tuberostemonines [688], (−)-kendomycin [1125], pochonin D [1126], (−)-223A [1127], coleophomones B-D [1128], brevetoxin B [130], garsubellin A [45], fostriecin [48], 11-acetoxy-4-deoxyasbestin D [1129], (+)-cyclophellitol [1130], ␤-C-glycosides [50], zoapatanol [247], deoxymannojirimycin and swainsonine [1131], valienamine [1132], A 3 adenosine recetor agonists [1133], vincantril [810], (−)-perhydrohistrionicotoxin [1134], annonaceous acetogenins [1135], deoxycombrestatin A-4 analogs [1136], (+)-lentiginosine and analogs [1137], N-malayamycin A [1138], (−)-salicylhalamides A and B [938], oxytocin analogs [1139], steroid-like compounds [440], (−)-isoprelaurefucin [338], halichondrin B [1140], (−)-microcarpalide and (+)-lethaloxin [1141,1142], anamarine …”

“…Nucleophilic substitution of an alkyl, alkenyl, and alkyl iodides or triflates with organocopper reagents were used in syntheses of sordaricin [1619], (−)-salicylhalamides A and B [938], (−)-kainic acid [1620], (+)-bistramide C [801] and (+)-discodermolide analogues [1621]. Two consecutive carbocuprations of a diyne was used in a synthesis of F-J ring-fragment of gambieric acid (Eq.…”

Isolation and Biological Evaluation of 8-epi-Malyngamide C from the Floridian Marine Cyanobacterium Lyngbya majuscula

“…Deprotection using K 2 CO 3 29 gave the inverted product that had 1 H and 13 C NMR spectra identical to malyngamide C, which we isolated from sea hares collected in the Cook Islands in the Pacific Ocean (see Supporting Information). The spectroscopic data also matched those previously reported for malyngamide C 1.…”

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

“…A forte dependência da estereosseletividade da reação de fechamento de anéis em função da proteção ao nível da hidroxila fenólica OH-13 foi demonstrada por Georg e colaboradores, usando o catalisador de Grubbs-I 3 (Esquema 17) 61 . Na presença da hidroxila fenólica livre, o macrociclo de 12 membros 60 com a ligação dupla Z é obtido como produto majoritário a partir do dieno 59 (R = H).…”