Open-chain remote stereocontrol using allylgermanes

Thomas, Eric J.; Weston, Astrid

doi:10.1016/j.tet.2014.06.053

Cited by 2 publications

(1 citation statement)

References 24 publications

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“…To be on the safe side, we also searched through the literature for precedents and managed to find several pairs of ( E )-/( Z )-isomers , (Figure ) whose optical rotations were opposite in sign. It thus appears that (at least when CC bonds are conjugated to carbonyl groups and the CC bonds are not far away from stereogenic centers) the geometry of the CC bonds indeed may affect the signs of optical rotations, though no one seems to have ever explicitly mentioned this phenomenon to date…”

Section: Resultsmentioning

confidence: 99%

Synthesis of (+)-Panamonon B, 7-epi-Panamonon B, and Their (Z)-Isomers

2021

J. Org. Chem.

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Metrics & MoreArticle Recommendations * sı Supporting Information ABSTRACT: (+)-Panamonon B was synthesized with the key quaternary center (of a predefined absolute configuration) installed using Stoltz asymmetric allylation. The C-5 ketone functionality and the cross-conjugated enone moiety in the side chain were introduced via a photosensitized [2+4] cycloaddition of singlet oxygen to diene silyl enol ether and an aldol condensation under the conditions of Sugiura, respectively. The 1 H and 13 C NMR of the synthetic and natural samples were fully consistent with each other. However, because two samples showed opposite signs for optical rotations, they must be antipodes to one another. The synthesis also provided valuable chances to observe unexpected, yet rather intriguing, phenomena such as a bulky substituent in an axial position of a cyclohexane ring and (E)and (Z)-isomers with opposite signs for optical rotations despite their identical stereogenic centers. The rare occurrence of a bulky substituent in an axial position of a cyclohexane ring is rationalized as a consequence of the presence of a quaternary center and formation of the five-membered lactone fused to the six-membered ring, while the so far unnoticed influence of CC geometry on optical rotation is shown to be consistent with the information encapsulated in several discrete pairs of similar compounds retrieved from the literature.

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Section: Resultsmentioning

confidence: 99%

Synthesis of (+)-Panamonon B, 7-epi-Panamonon B, and Their (Z)-Isomers

2021

J. Org. Chem.

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ChemInform Abstract: Open‐Chain Remote Stereocontrol Using Allylgermanes.

Thomas

Weston

2015

ChemInform

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Open-Chain Remote Stereocontrol Using Allylgermanes. -In reactions of allylgermanes with aldehydes promoted by tin(IV) halides 1,5-and 1,6-stereocontrol is achieved. In many cases, yields and stereoselectivities are better compared with reactions using the corresponding allylstannanes. Also, the influence of enylgermane geometry on the overall stereoselectivity is investigated. Reactions using the Z-isomers are more selective than the E-isomeric germanes. -(THOMAS*, E. J.; WESTON, A. P.; Tetrahedron 70 (2014) 40, 7253-7267, http://dx.

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Open-chain remote stereocontrol using allylgermanes

Cited by 2 publications

References 24 publications

Synthesis of (+)-Panamonon B, 7-epi-Panamonon B, and Their (Z)-Isomers

Synthesis of (+)-Panamonon B, 7-epi-Panamonon B, and Their (Z)-Isomers

ChemInform Abstract: Open‐Chain Remote Stereocontrol Using Allylgermanes.

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