Luiz C. Dias

ENANTIOSELECTIVE TOTAL SYNTHESIS OF ALTOHYRTIN C (SPONGISTATIN 2)

Abstract The first total synthesis of a spongipyran macrolide, altohyrtin C, is described. The convergent synthesis strategy relies on a regioselective macrolactonization, a stereoselective Wittig coupling of the two major synthetic fragments, a complex anti aldol reaction to join the C1–C15 and C16–C28 spiroketal regions, and an anomeric sulfone acylation to join the C29–C37 and C38–C43 pyran regions. The incorporation of the C44–C51 sidechain in the final stages of the synthesis establishes a viable route for the construction of variants in this pharmacologically important region. Methodological developments en route to the total synthesis include a 1,5 anti-selective methyl ketone aldol reaction and a diastereoselective approach to Lewis acid mediated β-C-glycosidation. Completion of the synthesis has confirmed the stereochemical assignments proposed in the altohyrtin series and has established the identity of the altohyrtin and spongistatin marine macrolides.

Chiral Lewis acid catalysts in diels-Alder cycloadditions: mechanistic aspects and synthetic applications of recent systems

This review summarizes the recent progress which has been made in the use of chiral Lewis Acid catalysts in Diels-Alder cycloaddition reactions. Chiral catalysts containing aluminum, boron, titanium, copper, lanthanides, magnesium and transition-metals are critically reviewed. Structural studies on Lewis acid carbonyl complexes and synthetic applications of recent systems are specifically discussed.

Chiral Lewis Acid Catalyzed Ene-Reactions

This review covers recent progress in the use of chiral Lewis acid catalysts in ene-reactions which involve carbonyl and imine compounds as enophiles. Chiral Lewis acid catalysts containing aluminum, titanium, ytterbium and copper are critically reviewed. Synthetic applications of recent systems are specifically discussed. Dedicated to the Brazilian Chemical Society

Total synthesis of (+)-crocacin D.

[structure: see text] The total synthesis of (+)-crocacin D is described. The convergent asymmetric synthesis relies on the use of a Stille cross-coupling between an (E)-vinyl stannane with an (E)-vinyl iodide to establish the (E,E)-dienamide moiety followed by a mild and efficient copper-catalyzed coupling between (+)-crocacin C and a (Z)-vinyl iodide to establish the challenging (Z)-enamide function.

Synthetic studies directed toward the total synthesis of dolabriferol

Herein we report our results towards the total synthesis of (−)-dolabriferol, describing the synthesis of fragments C1–C9 and C10–C21. This convergent asymmetric approach relies on the use of a common Weinreb amide precursor for the preparation of both fragments, an efficient anti-aldol reaction followed by Zn(BH4)2 reduction to give a 1,3-syn diol, a selective oxidation of a triol under Swern conditions with concomitant lactol formation, and a diastereoselective epoxidation of an allylic alcohol with m-CPBA followed by an efficient epoxide opening with Me2CuCNLi2.

Tandem N-acyliminium-Michael addition reaction. An efficient total Synthesis of the quinolizidine alkaloids (+/−)-myrtine and (+/−)-lasubine II.

Abstract A short and effecient preparation of the quinolizidine alkaloids (±)-lasubine II ( 1 ) and (±)-myrtine ( 2 ) is described featuring the tandem N-acyliminium ion- Michael addition of 2-trimethylsilyloxy butadienes to ethoxycarbamate 4 promoted by TMSOTf.

Total Synthesis of (−)-Goniotrionin

A stereoselective total synthesis of the reported structure of goniotrionin (4) has been accomplished. The key steps involved the opening of a chiral epoxide, a highly diastereoselective Mukaiyama aerobic oxidative cyclization, a selective 1,2-syn Mukaiyama aldol reaction, and a Noyori reduction.

Synthesis of ferrocenyl oxindole compounds with potential anticancer activity

Compostos oxindol-ferrocenos com potencial atividade anticâncer foram preparados a partir de reacoes de oxindois substituidos e carboxaldeido-ferroceno na presenca de KOH como catalisador. Os produtos foram caracterizados por dados espectroscopicos incluindo RMN de 1H e 13C, infravermelho e espectrometria de massas. As configuracoes E e Z foram estabelecidas por experimentos de nOe ou NOESY.

1,5-Asymmetric Induction in Boron-Mediated Aldol Reactions of β-Alkoxy Methylketones

Good levels of substrate-controlled, 1,5- syn-stereoinduction are obtained in boron-mediated aldol reactions of beta-trichloromethyl-beta-alkoxy and beta-trifluoromethyl-beta-alkoxy methylketones with achiral aldehydes, independent of the nature of the beta-alkoxy protecting group (TBS or PMB). In the case of boron aldol reactions of beta-aryl-beta-alkoxy methylketones, the 1,5- anti-adducts were obtained with high levels of diastereoselectivity only with a beta-OPMB group.

Trimethylsilyl Trifluoromethanesul Fonate (Tmsotf) Catalyzed Amidoalkylation of Silylenolethers. Stereocontrolled Syntheses of (+/-)-Sedamine and (+/-)-Norsedamine

Abstract Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed addition of 1-trimethylsilyloxy-1-phenylethene to N-ethoxycarbonyl-and N-tert-butoxycarbonyl-2-ethoxypiperidines (3d and 3b, respectively) afforded the corresponding ketocarbamates 4a and 4b, in excellent yields. Stereoselective conversion to (±)-norsedamine (7) and (±)-sedamine (8) is described.