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Journal ArticleDOI

Carbocycles from donor–acceptor cyclopropanes

21 Jan 2015-Organic and Biomolecular Chemistry (The Royal Society of Chemistry)-Vol. 13, Iss: 3, pp 655-671
TL;DR: This review summarizes research directed towards the formation of carbocyclic adducts from donor-acceptor cyclopropanes and focuses on annulation and cycloaddition reactions mediated by Lewis or protic acid, bases, or thermal conditions.
Abstract: This review summarizes research directed towards the formation of carbocyclic adducts from donor–acceptor cyclopropanes. The focus of the review is on annulation and cycloaddition reactions (both inter- and intramolecularly) mediated by Lewis or protic acid, bases, or thermal conditions. Rearrangements resulting in carbocycles and those reactions mediated by transition metal catalysis have been excluded.
Citations
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Journal ArticleDOI
TL;DR: The phosphoramide-based bifunctional catalysts achieved better enantiofacial control than the analogous H-bond-donor-derived catalysts in these reactions, suggesting the potential of the former in new chiral catalyst development.
Abstract: Conspectus3,3-Disubstituted oxindoles are widely distributed in natural products, drugs, and pharmaceutically active compounds. The absolute configuration and the substituents on the fully substituted C3 stereocenter of the oxindole often significantly influence the biological activity. Therefore, tremendous efforts have made to develop catalytic enantioselective syntheses of this prominent structural motif. Research in this area is further fueled by the ever-increasing demand for modern probe- and drug-discovery programs for synthetic libraries of chiral compounds that are derived from privileged scaffolds with high structural diversity. Notably, the efficient construction of fully substituted C3 stereocenters of oxindole, tetrasubstituted or all-carbon quaternary, spirocyclic or not, also becomes a test ground for new synthetic methodologies.We have been engaged in developing efficient methods for diversity-oriented synthesis of chiral 3,3-disubstituted oxindoles from readily available starting material...

276 citations

Journal ArticleDOI
TL;DR: This Review summarizes major advances in nonenzymatic, transition-metal-promoted dynamic asymmetric transformations reported between 2005 and 2015.
Abstract: Stereoconvergent catalysis is an important subset of asymmetric synthesis that encompasses stereoablative transformations, dynamic kinetic resolutions, and dynamic kinetic asymmetric transformations. Initially, only enzymes were known to catalyze dynamic kinetic processes, but recently various synthetic catalysts have been developed. This Review summarizes major advances in nonenzymatic, transition-metal-promoted dynamic asymmetric transformations reported between 2005 and 2015.

218 citations

Journal ArticleDOI
TL;DR: The development of enantioselective methods for the ring opening of cyclopropanes has grown from a proof of concept stage to a broad range of methods for accessing enantioenriched building blocks, and further extensive developments can be expected in the future.
Abstract: This review describes the development of enantioselective methods for the ring opening of cyclopropanes. Both approaches based on the reaction of nonchiral cyclopropanes and (dynamic) kinetic resolutions and asymmetric transformations of chiral substrates are presented. The review is organized according to substrate classes, starting by the more mature field of donor-acceptor cyclopropanes. Emerging methods for enantioselective ring opening of acceptor- or donor-only cyclopropanes are then presented. The last part of the review describes the ring opening of more reactive three-membered rings substituted with unsaturations with a particular focus on vinylcyclopropanes, alkylidenecyclopropanes, and vinylidenecyclopropanes. In the last two decades, the field has grown from a proof of concept stage to a broad range of methods for accessing enantioenriched building blocks, and further extensive developments can be expected in the future.

208 citations

Journal ArticleDOI
TL;DR: This comprehensive review on cycloaddition reactions of enoldiazo compounds, with emphasis on methodology development, mechanistic insight, and catalyst-controlled chemodivergence, aims to provide inspiration for future discoveries in the field and to catalyze the application of enoldsiazo reagents by the wider synthetic community.
Abstract: Enoldiazo esters and amides have proven to be versatile reagents for cycloaddition reactions that allow highly efficient construction of various carbocycles and heterocycles. Their versatility is exemplified by (1) [2+n]-cycloadditions (n = 3, 4) by the enol silyl ether units of enoldiazo compounds with retention of the diazo functionality to furnish α-cyclic-α-diazo compounds that are themselves subject to further transformations of the diazo functional group; (2) [3+n]-cycloadditions (n = 1–5) by metallo-enolcarbenes formed by catalytic dinitrogen extrusion from enoldiazo compounds; (3) [2+n]-cycloadditions (n = 3, 4) by donor–acceptor cyclopropenes generated in situ from enoldiazo compounds that produce cyclopropane-fused ring systems. The role of dirhodium(II) and the emergence of copper(I) catalysts are described, as are the different outcomes of reactions initiated with these catalysts. This comprehensive review on cycloaddition reactions of enoldiazo compounds, with emphasis on methodology development, mechanistic insight, and catalyst-controlled chemodivergence, aims to provide inspiration for future discoveries in the field and to catalyze the application of enoldiazo reagents by the wider synthetic community.

175 citations

Journal ArticleDOI
TL;DR: A comprehensive overview of the direct borylation of less reactive C-Het and C-C bonds has become highly important to get efficiency and functional-group compatibility in organoborons.
Abstract: Organoborons have emerged as versatile building blocks in organic synthesis to achieve molecular diversity and as carboxylic acid bioisosteres with broad applicability in drug discovery Traditiona

171 citations

References
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Journal ArticleDOI
TL;DR: Telmisartan was equivalent to ramipril in patients with vascular disease or high-risk diabetes and was associated with less angioedema and a increased risk of hypotensive symptoms.
Abstract: Background In patients who have vascular disease or high-risk diabetes without heart failure, angiotensin-converting–enzyme (ACE) inhibitors reduce mortality and morbidity from cardiovascular causes, but the role of angiotensin-receptor blockers (ARBs) in such patients is unknown. We compared the ACE inhibitor ramipril, the ARB telmisartan, and the combination of the two drugs in patients with vascular disease or high-risk diabetes. Methods After a 3-week, single-blind run-in period, patients underwent double-blind randomization, with 8576 assigned to receive 10 mg of ramipril per day, 8542 assigned to receive 80 mg of telmisartan per day, and 8502 assigned to receive both drugs (combination therapy). The primary composite outcome was death from cardiovascular causes, myocardial infarction, stroke, or hospitalization for heart failure. Results Mean blood pressure was lower in both the telmisartan group (a 0.9/0.6 mm Hg greater reduction) and the combination-therapy group (a 2.4/1.4 mm Hg greater reduction) than in the ramipril group. At a median follow-up of 56 months, the primary outcome had occurred in 1412 patients in the ramipril group (16.5%), as compared with 1423 patients in the telmisartan group (16.7%; relative risk, 1.01; 95% confidence interval [CI], 0.94 to 1.09). As compared with the ramipril group, the telmisartan group had lower rates of cough (1.1% vs. 4.2%, P<0.001) and angioedema (0.1% vs. 0.3%, P = 0.01) and a higher rate of hypotensive symptoms (2.6% vs. 1.7%, P<0.001); the rate of syncope was the same in the two groups (0.2%). In the combination-therapy group, the primary outcome occurred in 1386 patients (16.3%; relative risk, 0.99; 95% CI, 0.92 to 1.07); as compared with the ramipril group, there was an increased risk of hypotensive symptoms (4.8% vs. 1.7%, P<0.001), syncope (0.3% vs. 0.2%, P = 0.03), and renal dysfunction (13.5% vs. 10.2%, P<0.001). Conclusions Telmisartan was equivalent to ramipril in patients with vascular disease or highrisk diabetes and was associated with less angioedema. The combination of the two drugs was associated with more adverse events without an increase in benefit. (ClinicalTrials.gov number, NCT00153101.)

3,262 citations

Journal ArticleDOI
TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.

805 citations