Angélica Venturini Moro

Highly Regio- and Stereoselective Heck Reaction of Allylic Esters with Arenediazonium Salts: Application to the Synthesis of Kavalactones

A highly efficient palladium-catalyzed Heck reaction of allylic esters with arenediazonium salts is described. The reaction proceeds under mild conditions, with excellent to total regio- and stereochemical control and with retention of the traditional leaving group. Furthermore, the generality of the present methodology is illustrated by the short total synthesis of the natural kavalactones, yangonine, (+/-)-methysticin, and (+/-)-dihydromethysticin.

Copper-catalyzed hydroboration of propargyl-functionalized alkynes in water

The Cu-catalyzed hydroboration of alkynes in operationally simple and environmentally friendly conditions is reported. The reactions are performed in water, at room temperature, under micellar catalysis. Conditions to form the α or β borylated products selectively have been found and as an application a protocol for the tandem hydroboration/Suzuki coupling in water was developed.

Identification and ultra‐high‐performance liquid chromatography coupled with high‐resolution mass spectrometry characterization of biosurfactants, including a new surfactin, isolated from oil‐contaminated environments

Biosurfactant‐producing bacteria were isolated from samples collected in areas contaminated with crude oil. The isolates were screened for biosurfactant production using qualitative drop‐collapse test, oil‐spreading and emulsification assays, and measurement of their tensoactive properties. Five isolates tested positive for in the screening experiments and displayed decrease in the surface tension below 30 mN m−1. The biosurfactants produced by these isolates were further investigated and their molecular identification revealed that they are bacteria related to the Bacillus genus. Additionally, the biosurfactants produced were chemically characterized via UHPLC‐HRMS experiments, indicating the production of surfactin homologues, including a new class of these molecules.

Stereoselective heck-matsuda arylations of chiral dihydrofurans with arenediazonium tetrafluoroborates; an efficient enantioselective total synthesis of (-)-isoaltholactone

The Heck-Matsuda arylation of chiral 2-( S)-hydroxy-methyl dihydrofurans (endocyclic enolethers) and its derivatives, employing arenediazonium tetrafluoroborates, was developed into a highly efficient, practical and diastereoselective synthetic process. This methodology was applied to the total synthesis of the styryllactone (-)-isoaltholactone in seven steps with an overall yield of ~25%, from the readily available chiral 2-hydroxymethyldihydrofuran. The strategy permits the synthesis of several other aromatic analogues of isoaltholactone.

3-Hydroxy-2-phenyl-2,3,3a,7a-tetrahydro-1H,5H-pyrano[3,2-b]pyrrol-5-one: crystal structure and Hirshfeld surface analysis

Twisted and half-chair conformations are found for the five- and six-membered rings comprising the fused-ring system in the title isoaltholactone derivative. In the molecular packing, linear supramolecular chains sustained by hydroxy-O—H⋯N(amine) hydrogen bonding are evident.

Modelos estereoquímicos de adição à carbonila

STEREOCHEMICAL MODELS FOR CARBONYL ADDITION. The stereochemical control in the generation of new stereogenic centers is of paramount importance in organic chemistry. In this context, diastereoselective additions to carbonyl compounds bearing a stereogenic center at the α-position are of particular importance, since an increase in molecular complexity can be achieved by constructing a new bond, together with the introduction of a new stereocenter. Despite the relevance of the topic, it is discussed only briefly in several of the most popular organic chemistry textbooks, or not discussed at all. The present article intends to discuss the evolution of stereochemical models for 1,2-induction and present to students a tool to understand and predict the stereochemical outcome of addition of nucleophiles to aldehydes and ketones bearing a stereogenic center at the α-position.

[(2S,5R)-1-Methyl-5-phenyl­pyrrolidin-2-yl]diphenyl­methanol

In the title compound, C24H25NO, the phenyl and diphenylmethanol substituents are syn to each other. The pyrrolidine ring has an envelope conformation with the flap atom being the C atom bearing the phenyl substituent. The hydroxy group forms an intramolecular hydrogen bond with the pyrrolidine N atom, and the phenyl rings lie to same side of the molecule. The crystal packing features C—H⋯π interactions. Two slightly displaced co-planar orientations were found for one of the phenyl rings; the major component had a site-occupancy factor of 0.782u2005(15).

Highly Regio- And Stereoselective Heck Reaction Of Allylic Esters With Arenediazonium Salts: Application To The Synthesis Of Kavalactones.

A highly efficient palladium-catalyzed Heck reaction of allylic esters with arenediazonium salts is described. The reaction proceeds under mild conditions, with excellent to total regio- and stereochemical control and with retention of the traditional leaving group. Furthermore, the generality of the present methodology is illustrated by the short total synthesis of the natural kavalactones, yangonine, (+/-)-methysticin, and (+/-)-dihydromethysticin.