trans-Cycloalkenes. Part 11. trans-Cyclonona-1,2,6-triene, a transient precursor of 2,3-divinylcyclopentene

CONNELL, A. C.; Whitham, G. H.

doi:10.1039/p19830000989

Cited by 5 publications

(1 citation statement)

References 6 publications

(19 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This same type of rearrangement will proceed in diallenes that are not contained within ring systems [28]. 1,2,6·Cyclononatriene, 40, uses a [3,3] sigmatropic shift to contract [29] to 1,5-divinylcyclopentene, 41. 1,2,4-Cyclodecatriene 42 utilizes a 1,5 hydrogen shift followed by a [3,3] which determines the conformations and torsional barriers.…”

Section: Medium and Large·ring Allenesmentioning

confidence: 99%

Preparation and Reactions of Cyclic Allenes

Thies

1985

Israel Journal of Chemistry

View full text Add to dashboard Cite

show abstract

Section: Medium and Large·ring Allenesmentioning

confidence: 99%

Preparation and Reactions of Cyclic Allenes

Thies

1985

Israel Journal of Chemistry

View full text Add to dashboard Cite

show abstract

Highly Modular P‐O‐P Ligands for Asymmetric Hydrogenation

2008

View full text Add to dashboard Cite

Abstract:The preparation of a library of new P-O-P ligands (phosphine-phosphites and phosphinephosphinites), easily available in two synthetic steps from enantiopure Sharpless epoxy ethers, is reported. The "lead" catalyst of the series has proven to have outstanding catalytic properties in the rhodium-catalysed asymmetric hydrogenation of a wide variety of functionalised alkenes (16 examples). The excellent performance and modular design of the catalysts makes them attractive for future applications.Keywords: asymmetric catalysis; hydrogenation; ligand design; phosphane ligands; phosphite ligands; rhodium Asymmetric hydrogenation can be considered a well established synthetic methodology that has already been incorporated into the standard "asymmetric tool-box" of the synthetic community.[1] From a practical perspective, it is one of the most efficient methodologies for the generation of new stereogenic carbon centres. There have been several significant breakthroughs in the field [1] and now a myriad of chiral Ru, Rh and Ir coordination compounds (mostly phosphorus-containing derivatives) capable of mediating the addition of H 2 to prochiral C=C, C=N and C=O bonds with very high enantioselectivities are known.[1] The development of commercial processes [2] has rendered this transformation highly desirable to both academia and industry. However, despite the remarkably advanced state of the field, many groups are still actively researching new catalytic systems that show higher activity and/or improved enantioselectivity for challenging substrates. In other cases, research efforts are directed to the development of chiral ligands with an attractive industrial profile, which ultimately means that they should induce high enantioselectivity, be easily prepared and not fall into the claims of any patent currently in force. While computational techniques are becoming increasingly important in the design of new chiral catalysts, [3] many approaches still rely to a great extent on trialand-error. Not surprisingly, combinatorial and highthroughput synthetic strategies [4] have led to the development of some highly efficient monodentate and bidentate phosphorus-containing ligands for asymmetric hydrogenation, utilising either standard covalent chemistry [4c,5] or supramolecular interactions. [6] In a complementary way, ligand tuning in asymmetric catalysis has allowed the rapid development of efficient catalytic systems. We [3a,7] and others [8] have shown that the modular nature of ligands facilitates the tuning of their performance by modifying the stereoelectronic properties of the different modular fragments (modules). This encouraged us to design a new family of P-O-P ligands 3 derived from enantiopure epoxides and the work described here details our initial efforts in this area together with their application in the asymmetric hydrogenation of functionalised alkenes.We envisaged that the chiral epoxides 1 could be converted into the P-O-P ligands 3, as shown in Scheme 1. Epoxide ring-opening with nucleophilic triv...

show abstract

Ring‐opening of Epoxides Mediated by Frustrated Lewis Pairs

Krachko

Nicolas

Ehlers

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

Treatment of the preorganized frustrated Lewis pairs (FLPs) tBu PCH BPh (1) and o-Ph P(C H )BCat (Cat=catechol) (4) with 2-methyloxirane, 2-phenyloxirane and 2-(trifluoromethyl)oxirane resulted in epoxide ring-opening to yield the six- and seven-membered heterocycles 2 a-c and 5 a-c, respectively. These zwitterionic products were characterized spectroscopically, and compounds 2 a, 2 b, 5 a and 5 c were structurally characterized by single-crystal X-ray structure analyses. Based on computational and kinetic studies, the mechanism of these reactions was found to proceed via activation of the epoxide by the Lewis acidic borane moiety followed by nucleophilic attack of the phosphine of a second FLP molecule. The resulting chain-like intermediates afford the final cyclic products by ring-closure and concurrent release of the second equivalent of FLP that behaves as catalyst in this reaction.

show abstract

trans-Cycloalkenes. Part 11. trans-Cyclonona-1,2,6-triene, a transient precursor of 2,3-divinylcyclopentene

Cited by 5 publications

References 6 publications

Preparation and Reactions of Cyclic Allenes

Preparation and Reactions of Cyclic Allenes

Highly Modular P‐O‐P Ligands for Asymmetric Hydrogenation

Ring‐opening of Epoxides Mediated by Frustrated Lewis Pairs

Contact Info

Product

Resources

About