3 research outputs found
Concise Synthesis of the Isothiourea Organocatalysts Homobenzotetramisole and Derivatives
A concise approach to the synthesis
of homobenzotetramisole and
derivatives is described. Our strategy features a one-pot acylation–cyclization
of 2-aminobenzothiazole with α,β-unsaturated acid chlorides
to afford annulated pyrimidones. Subsequent Grignard addition followed
by acid-promoted dehydration and reduction provides good overall yields
of the title compounds in three steps and in quantities up to 10 g.
The synthesis employs low-cost and readily available starting materials
and enables access to both optical antipodes of these increasingly
useful nucleophilic catalysts following chiral separation
3‑Alkenyl-2-silyloxyindoles in Vinylogous Mannich Reactions: Synthesis of Aminated Indole-Based Scaffolds and Products
The first Lewis acid
catalyzed vinylogous Mukaiyama-type Mannich
addition of 3-alkenyl-2-silyloxyindoles to in situ generated <i>N</i>-Boc imines has been established, which affords chiral
α-alkylidene-δ-amino-2-oxindole products with good efficiency
and complete γ-site- and <i>Z</i>-selectivity. The
reaction is wide in scope, as it can be applied with equal convenience
to different silyloxyindole donors and aromatic or aliphatic aminal-derived
aldimine acceptors. The utility of these scaffolds is demonstrated
by their easy transformation into either spirocyclopropane oxindole
or homotryptamine-like products, featuring nontraditional indole-based
skeleton connections
Enantioselective Synthesis of Cyclobutenes by Intermolecular [2+2] Cycloaddition with Non‑<i>C</i><sub>2</sub> Symmetric Digold Catalysts
The enantioselective intermolecular
gold(I)-catalyzed [2+2] cycloaddition
of terminal alkynes and alkenes has been achieved using non-<i>C</i><sub>2</sub>-chiral Josiphos digold(I) complexes as catalysts,
by the formation of the monocationic complex. This new approach has
been applied to the enantioselective total synthesis of rumphellaone
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