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A diastereoselective two-step strategy for the synthesis of densely functionalized 1-halocyclopentenes with several chiral centers has been developed. In the first step, a multicomponent alkynyl halo-Prins reaction joins an enyne, a carbonyl derivative, and either a chloride, bromide, or iodide to produce a cyclic ether intermediate. In the subsequent step, the intermediate is ionized to generate a halopentadienyl cation, which undergoes an interrupted halo-Nazarov cyclization. The products contain three new contiguous stereogenic centers, generated with a high level of stereocontrol, as well as a vinyl halide allowing for additional functionalization. The strategy creates two new carbon-carbon bonds, one carbon-halide bond, and one carbon-oxygen bond., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first synthesis of (±)-tetrapetalone A-Me aglycon is described. Key bond-forming reactions include Nazarov cyclization, a ring-closing metathesis promoted with complete diastereoselectivity by a chiral molybdenum-based complex, tandem conjugate reduction/intramolecular aldol cyclization, and oxidative dearomatization., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The requirement for new strategies for synthesizing five-membered carbocycles has driven an expansion in the study of the Nazarov cyclization. This renewed interest in the reaction has led to the discovery of several interesting new methods for generating the pentadienyl cation intermediate central to the cyclization. Methods reviewed include carbon-heteroatom ionization, functionalization of a double bond, nucleophilic addition, or electrocyclic ring opening. Additional variations employ unconventional substrates to produce novel pentacycles, such as the iso- and imino-Nazarov. Herein, we provide an overview of these unconventional, yet highly useful versions of the Nazarov cyclization.

The discovery and elucidation of a new Nazarov cyclization/Wagner-Meerwein rearrangement/oxidation sequence is described that constitutes an efficient strategy for the synthesis of 4-alkylidene cyclopentenones. DFT computations and EPR experiments were conducted to gain further mechanistic insight into the reaction pathways., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An approach toward the carbon framework of various sesquiterpenes from the herbertane and cuparane families is described, including the concise total synthesis of enokipodin B. The key step is the construction of the vicinal quarternary centers of the skeleton through a tandem Nazarov cyclization/Wagner-Meerwein rearrangement mediated by a copper(II) complex. During this study, it was also found that changing the ligand architecture on the copper(II) promoter improved the chemoselectivity of the cationic rearrangement., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bryostatins, a family of structurally complicated macrolides, exhibit an exceptional range of biological activities. The limited availability and structural complexity of these molecules makes development of an efficient total synthesis particularly important. This article describes our initial efforts towards the total synthesis of bryostatins, in which chemoselective and atom-economical methods for the stereoselective assembly of the ring C subunit were developed. A Pd-catalyzed tandem alkyne-alkyne coupling/6-endo-dig cyclization sequence was explored and successfully pursued in the synthesis of a dihydropyran ring system. Elaboration of this methodology ultimately led to a concise synthesis of the ring C subunit of bryostatins., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)