The first direct observation of an allylic [3,3] sigmatropic cyanate–isocyanate rearrangement

Banert, Klaus; Melzer, Antje

doi:10.1016/s0040-4039(01)01212-6

Cited by 20 publications

(7 citation statements)

References 16 publications

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“…In order to bring to light the formation of the transient allyl cyanate 3 by means of NMR spectroscopy, , we studied the formation of 4 from 2 using the experimental procedure B in CD 2 Cl 2 . In a surprising way, we observed the transformation of 2 into 4 at very low temperature.…”

Section: Resultsmentioning

confidence: 99%

Stereospecific Synthesis of α-Amino Allylsilane Derivatives through a [3,3]-Allyl Cyanate Rearrangement. Mild Formation of Functionalized Disiloxanes

et al. 2016

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An efficient asymmetric synthesis of α-amino allylsilane derivatives is reported. The strategy is based on a [3,3]-allyl cyanate sigmatropic rearrangement from enantioenriched γ-hydroxy alkenylsilyl compounds. The isocyanate intermediate can be trapped by several nucleophiles, opening the way for the preparation of unknown chiral functionalized compounds such as the α-ureido allylsilanes as well as carbamate derivatives. A computational study was conducted to rationalize the complete 1,3-chirality transfer of this kind of rearrangement. Moreover, starting from products bearing a phenyldimethyl silyl substituent, the α-amino silane derivatives or the corresponding disiloxanes can be obtained under hydrogenation conditions in an exclusive way according to the used catalyst.

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Section: Resultsmentioning

confidence: 99%

Stereospecific Synthesis of α-Amino Allylsilane Derivatives through a [3,3]-Allyl Cyanate Rearrangement. Mild Formation of Functionalized Disiloxanes

et al. 2016

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“…In 2001, the first direct observation, by NMR, of the [3,3]-sigmatropic cyanate to isocyanate rearrangement was made by Banert et al, allowing measurement of its activation parameters. 21 The large negative activation entropy (DS a o À100 J mol À1 K À1 ) is characteristic of a cyclic transition state. During this study it was furthermore demonstrated that this transposition is much more rapid than the analogous rearrangement of a propargylic cyanate to an allenyl isocyanate.…”

Section: [33]-sigmatropic Rearrangementsmentioning

confidence: 99%

Quaternary centres bearing nitrogen (α-tertiary amines) as products of molecular rearrangements

et al. 2011

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Quaternary centres bearing a nitrogen substituent (α-tertiary amines and their derivatives) are found in a variety of bioactive molecules but pose a major challenge in synthesis, particularly when enantiomeric purity is required. Approaches comparable to those used for tertiary alcohols are typically hampered by the poor electrophilicity of imines, requiring powerful nucleophiles that may also act as bases. A set of powerful alternative approaches make use of the rearrangement of readily available precursors, often (but not always) with formation of a new tertiary carbon to nitrogen bond. In this Feature Article we review the scope, limitations and specificities of some of these rearrangements in order to illuminate their synthetic potential.

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“…Allyl cyanates are rarely isolable and spontaneously rearrange to the corresponding isocyanates . For example, an activation enthalpy of 15 kcal mol –1 was calculated for the unhindered 3‐cyanoprop‐1‐ene, showing that such simple species are non‐isolable intermediates .…”

Section: Introductionmentioning

confidence: 99%

The Allyl Cyanate/Isocyanate Rearrangement: An Efficient Tool for the Stereocontrolled Formation of Allylic C–N Bonds

et al. 2017

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[3,3]‐Sigmatropic rearrangements represent powerful methods in the toolbox of synthetic organic chemists for the stereoselective construction of carbon–carbon as well as carbon–heteroatom bonds. Thus, the allyl cyanate/isocyanate rearrangement, although still underused for the preparation of allylamine derivatives, offers clear advantages over other similar methods. It usually occurs at or below ambient temperature with no need to use any metal catalyst, in a stereospecific way, and with a complete transfer of chirality. Moreover, combined with the high reactivity of the resulting isocyanates towards nucleophiles, this rearrangement gives access to various classes of compounds with wide structural and functional diversity. This microreview provides an overview of synthetic applications of this rearrangement since its discovery, with particular emphasis on its utility for the synthesis of complex nitrogen‐containing molecules such as natural products.

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The first direct observation of an allylic [3,3] sigmatropic cyanate–isocyanate rearrangement

Cited by 20 publications

References 16 publications

Stereospecific Synthesis of α-Amino Allylsilane Derivatives through a [3,3]-Allyl Cyanate Rearrangement. Mild Formation of Functionalized Disiloxanes

Stereospecific Synthesis of α-Amino Allylsilane Derivatives through a [3,3]-Allyl Cyanate Rearrangement. Mild Formation of Functionalized Disiloxanes

Quaternary centres bearing nitrogen (α-tertiary amines) as products of molecular rearrangements

The Allyl Cyanate/Isocyanate Rearrangement: An Efficient Tool for the Stereocontrolled Formation of Allylic C–N Bonds

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