Crystallographic Approach to the Origin of “Syn-Effect”

Inomata, Katsuhiko; Hirata, Takaki; Sasada, Y.; Asada, Toshio; Senda, Hitoshi; Kinoshita, Hideki

doi:10.1246/cl.1990.2153

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…Thus, when the reaction of 55 was performed under the above mentioned In-mediated rearrangement conditions, the rearranged product 56 was obtained in 64% yield. In contrast, the reaction of 57 with KHMDS in the presence of TMSCl and Et 3 N afforded isomer 58 in place of 56 [ 29 , 30 , 31 ].…”

Section: Indium-mediated Reformatsky-claisen Rearrangementmentioning

confidence: 99%

Recent Developments in the Reformatsky-Claisen Rearrangement

Ishihara

Hatakeyama

2012

Molecules

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The rearrangement of allyl α-bromoacetates with Zn dust is known as the Reformatsky-Claisen rearrangement. Whereas the Ireland-Claisen rearrangement has been widely used in the synthesis of a diverse range of natural products, the Zn-mediated Reformatsky-Claisen rearrangement has not been utilized so often. In this article, we will provide an overview of recent advances in the Reformatsky-Claisen rearrangement field, including the In-mediated Reformatsky-Claisen rearrangement we have recently developed.

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Section: Indium-mediated Reformatsky-claisen Rearrangementmentioning

confidence: 99%

Recent Developments in the Reformatsky-Claisen Rearrangement

Ishihara

Hatakeyama

2012

Molecules

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Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

Neier

Baak

Jaun

et al. 2022

Helvetica Chimica Acta

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The conformational studies in solution and in the solid state of substituted 6‐methyl‐4‐hydroxy‐2‐pyrones indicated that the substituents on the 4‐hydroxy group clearly favored the s‐cis arrangement towards the formal double bond. Steady state kinetic NOE measurements of the tert‐butyl, trimethylsilyl and the trimethylstannyl derivatives showed a marked preference for this conformation in solution. The structures determined by X‐ray diffraction demonstrated the exclusive presence of the same conformation in the solid state. In these three derivatives, the pertinent dihedral angle deviates only slightly from the value for coplanarity with the formal double bond. The predictions of the τ‐bond model are in accordance with the observations. The X‐ray structure of the trimethylstannyl derivative reveals pentacoordinated tin with short contacts to the oxygens at the 2 and 4 position of neighboring molecules. The tin center plays both the role of a protecting group for the 4‐hydroxy moiety and of a Lewis acid towards the 2‐carbonyl oxygen. The X‐ray structure of the stannyl derivative shows unique features which can be compared to the extended transition state of aldol reactions.

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