An efficient method for construction of tetrahydroisoquinoline skeleton via double cyclization process using ortho-vinylbenzaldehydes and amino alcohols: application to the synthesis of (S)-cryptostyline II

Iron Trichloride-Mediated Cascade Reaction of Aminosugar Derivatives for the Synthesis of Fused Tetrahydroisoquinoline-Tetrahydrofuran Systems

A method to obtain tetrahydroisoquinolines (THIQs) fused to tetrahydrofuran rings from aminosugar derivatives has been developed. The procedure relies on a key deprotection of benzyl ethers followed by a double-cyclization sequence, using FeCl₃ as the sole reagent. This tandem reaction affords the construction of novel fused polycyclic heterocycles with total stereochemical control.

Enantioselective synthesis of tetrahydroisoquinolines via catalytic intramolecular asymmetric reductive amination

A highly efficient intramolecular asymmetric reductive amination transformation catalyzed by an iridium complex of ^tBu-ax-Josiphos has been realized, providing an efficient access to various THIQ alkaloids.

Tandem Reaction Approaches to Isoquinolones from 2-Vinylbenzaldehydes and Anilines via Imine Formation-6π-Electrocyclization-Aerobic Oxidation Sequence

Two distinctive transition-metal-promoted aerobic oxidation protocols have been developed for the synthesis of isoquinolones from 2-vinylbenzaldehydes and aniline derivatives. Thus, the one-pot tandem reaction sequence of imine formation, thermal 6π-electrocyclization, followed by either Cu(OAc)₂-mediated or Pd(OAc)₂-catalyzed aerobic oxidation protocol allowed the ready access to isoquinolone derivatives. The control experiments revealed that the 1,2-dihydroisoquinoline intermediates from the 6π-electrocyclization of 1-azatrienes were aerobically oxidized to isoquinolones in the presence of either Cu(OAc)₂ or Pd(OAc)₂ catalyst.

The 6π-azaelectrocyclization of azatrienes. Synthetic applications in natural products, bioactive heterocycles, and related fields

Covering: 2006 to 2018 The application of the 6π-azaelectrocyclization of azatrienes as a key strategy for the synthesis of natural products, their analogs and related bioactive or biomedically-relevant compounds (from 2006 to date) is comprehensively reviewed. Details about reaction optimization studies, relevant reaction mechanisms and conditions are also discussed.

Direct access to substituted benzo[b]carbazoles through cascade annulation of 2-vinylbenzaldehydes with indoles

A highly efficient palladium-catalyzed cascade annulation of 2-vinylbenzaldehydes with indoles has been achieved to afford 6-(3-indolyl)benzo[b]carbazoles under mild conditions in good yield and with excellent regioselectivity.

Asymmetric Synthesis of Tetrahydroisoquinoline Alkaloids Using Ellman's Chiral Auxiliary

Chiral t-butylsulfinamide has been successfully employed for the stereoselective synthesis of 1-benzyl tetrahydroisoquinoline alkaloids. This is the first report on the synthesis of chiral 1-benzyltetrahydroisoquinoline natural products using tert-butylsulfinamide through a haloamide cyclization.

Asymmetric Synthesis of Isoquinoline Alkaloids: 2004-2015

In the past decade, the asymmetric synthesis of chiral nonracemic isoquinoline alkaloids, a family of natural products showing a wide range of structural diversity and biological and pharmaceutical activity, has been based either on continuation or improvement of known traditional methods or on new, recently developed, strategies. Both diastereoselective and enantioselective catalytic methods have been applied. This review describes the stereochemically modified traditional syntheses (the Pictet-Spengler, the Bischler-Napieralski, and the Pomeranz-Fritsch-Bobbitt) along with strategies based on closing of the nitrogen-containing ring B of the isoquinoline core by the formation of bonds between C₁-N₂, N₂-C₃, C₁-N₂/N₂-C₃, and C₁-N₂/C₄-C_4a atoms. Methods involving introduction of substituents at the C1 carbon of isoquinoline core along with syntheses applying various biocatalytic techniques have also been reviewed.

Tandem additions of 3,4-dihydroisoquinolines to γ-hydroxy-α,β-unsaturated ketones: a green and new access to oxazolo[2,3-a]tetrahydroisoquinolines

Addition reactions of various 3,4-dihydroisoquinoline derivatives with γ-hydroxy-α,β-unsaturated ketones were carried out in 15 min at room temperature without an additive, providing oxazolo[2,3-a]tetrahydroisoquinoline derivatives in high yields.

Stereoselective Lewis base catalyzed formal 1,3-dipolar cycloaddition of azomethine imines with mixed anhydrides

Stereoselective synthesis of pyrazolidinones via dipolar cycloaddition of azomethine imines with active esters under Lewis base catalysis is presented. The active esters are readily generated in situ from the corresponding acids. Products, which are obtained with excellent diastereocontrol and high enantioselectivity, contain along with the pyrazolidinone core also the tetrahydroisoquinoline structural motif. Theoretical studies give insight into the mechanism of the formal cycloaddition reaction.