Diastereoselective synthesis of substituted 2-amino-1,3-propanediols from Morita-Baylis-Hillman adducts

We report herein a new diastereoselective approach to substituted 2-amino-1,3-propanediols with anti relative stereochemistry from Morita-Baylis-Hillman (MBH) adducts. These structural moieties have been used as intermediates for the synthesis of several compounds with relevant pharmacological and commercial interest. In this strategy, substituted anti 2-amino-1,3-propanediols were readily prepared via ozonolysis of allylic diols obtained from MBH adducts, followed by a diastereoselective reductive amination of the substituted 2-oxo-1,3-propanediols. To demonstrate the synthetic utility of these aminodiols, they were transformed into substituted oxazolidin-2-ones, which were also used in the indirect determination of the relative stereochemistry of the aminodiols.Descrevemos nesse artigo uma abordagem diastereosseletiva, a partir de adutos de Morita-Baylis-Hillman (MBH), para a preparação de sistemas 2-amino-1,3-propanodióis substituídos com estereoquímica relativa anti. Estas unidades estruturais têm sido utilizadas como intermediárias para a síntese de diversas substâncias de interesse farmacológico e comercial. Nessa estratégia, os anti 2-amino-1,3-propanodióis foram facilmente preparados por ozonólise de dióis alílicos obtidos de adutos de MBH, seguido de uma aminação redutiva diastereosseletiva dos 2-oxo-1,3-propanodióis. Para demonstrar a utilidade desses aminodióis, eles foram transformados em oxazolidin-2-onas substituídas, que também foram utilizadas na determinação indireta da configuração relativa dos aminodióis.285293Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Catalytic Enantioselective Synthesis of Allylic Boronates Bearing a Trisubstituted Alkenyl Fluoride and Related Derivatives

The first catalytic method for diastereo- and enantioselective synthesis of allylic boronates bearing a Z-trisubstituted alkenyl fluoride is disclosed. Boryl substitution is performed with either a Z- or E-allyldifluoride and is catalyzed by bisphosphine/Cu complexes, affording products in up to 99 % yield with >98:2 Z/E selectivity and 99:1 enantiomeric ratio. A variety of subsequent modifications are feasible, and notable examples are diastereoselective additions to aldehydes/aldimines to access homoallylic alcohols/amines containing a fluorosubstituted stereogenic quaternary center

Catalytic Enantioselective Synthesis of Amino Skipped Diynes

The Cu-catalyzed synthesis of nonracemic 3-amino skipped diynes via an enantiodetermining C–C bond formation is described using StackPhos as ligand. Despite challenging issues of reactivity and stereoselectivity inherent to these chiral skipped diynes, the reaction tolerates an extremely broad substrate scope with respect to all components and provides the title compounds in excellent enantiomeric excess. The alkyne moieties are demonstrated here to be useful synthetic handles, and 3-amino skipped diynes are convenient building blocks for enantioselective synthesis

Controlling Regiochemistry in the Gold-Catalyzed Synthesis of Unsaturated Spiroketals

A novel gold-catalyzed synthesis of unsaturated spiroketals that addresses regioselectivity issues commonly reported in metal-catalyzed spiroketalization of alkynes is reported. The reaction sequence is regulated by an acetonide protecting group which undergoes extrusion of acetone to deliver the desired spiroketals in good yields and diastereoselectivities. The reaction, which is carried out under very mild conditions employing AuCl as the catalyst, should be widely applicable in the synthesis of a broad range of spiroketals

Incorporation of Axial Chirality into Phosphino-Imidazoline Ligands for Enantioselective Catalysis

A complementary strategy for ligand tuning that enables controlling ligand conformation is described here. The concept is demonstrated with new ligands that are employed in the catalytic enantioselective preparation of the highly important C2-aminoalkyl five-membered heterocycle motif. The alkynylation/cyclization sequence developed here is convergent, highly modular, and allows for a complementary scope to the heteroarylation of imines. This new ligand platform should offer new possibilities for expanding the use of PHIM-type ligands in a large variety of new transformations