Rearrangement allyl cyanates

An account has appeared166 of [3,3]-(and [2,3]-)sigmatropic rearrangements of propargyl precursors that lead to the synthesis of allenes bearing functional groups with at least two heteroatoms (see Scheme 36). The allyl cyanate to isocyanate rearrangement has been established as a new synthetic method for the construction... 

Y. Ichikawa, M. Osada, I. I. Ohtani, and M. Isobe, A new synthetic method for the preparation of amino sugars through an allyl cyanate-to-isocyanate rearrangement, J. Chem. Soc., Perkin Trans. 1, (1997) 1449-1455. 

Allyl cyanates undergo a [3,3] sigmatropic rearrangement to allyl isocyanates, as depicted in reaction 36. ... 

Synthesis of nitrogen-containing natural products using allyl cyanate-to-isocyanate rearrangement 06Y96. 

A synthesis of the marine diterpene geranyllinaloisocyanide 1652 has been successfully accomplished by a novel regioselective allylamine construction, which is achieved by an allyl cyanate-to-isocyanate rearrangement 1649 —> 1650. The resulting formamide 1651 is dehydrated with triphenylphosphane/tetrabromomethane to give the geranyllinaloisocyanide 1652 in 82% yield [1226]. 

Ichikawa and co-workers have published a number of papers disclosing an allyl cyanate to isocyanate rearrangement and its application to the synthesis of aminosugars [44,45]. A nitrogen substituent can be introduced into the pyra-... 

The vapor-phase chlorination reaction occurs at approximately 200-300°C. The dichlorobutene mixture is then treated with NaCN or HCN in presence of copper cyanide. The product 1,4-dicyano-2-butene is obtained in high yield because allylic rearrangement to the more thermodynamically stable isomer occurs during the cyanation reaction ... 

The 5-(2-alkenyloxy)thiatriazoles on thermal degradation gave alkenyl isocyanates by a presumed allylic rearrangement of the expected 2-alkenyl cyanates.54 Although the data do not exclude decomposition via intramolecular cyclic attack at the 4-position in the ring followed by very rapid decomposition of the 4-substituted thiatriazolines, these... 

Entries 1 and 2 in Table 8 are examples of an overall antarafacial 1,3-transposition of a hydroxy group by selenium compounds20,21. Treatment of the alcohols with 2-nitrophenyl seleno-cyanate in the presence of tributylphosphine gave the selenide with inversion of configuration. Oxidation with hydrogen peroxide led to the selenoxide, which rearranged suprafacially to the allylic alcohol. 

This compound undergoes rearrangement the same as ammonium cyanate and thio-urea is obtained. With a soluble mercuric salt ammonium thiocyanate precipitates mercuric thio-cyanate which on heating swells up into phantastic shapes which are known as Pharaoh s serpents. The alkyl thio-cyanates are known and have been discussed (p. 74). Allyl-thio-cyanate is a constituent of oil of garlic. These... 

Banert, K., Melzer, A. The first direct observation of an allylic [3,3] sigmatropic cyanate-isocyanate rearrangement. Tetrahedron Lett. 2001, 42,6133-6135. 

Prior chapters have covered the use of transition metals in asymmetric hydrogenations ( 6.2 and 7.1), hydroborations ( 7.3), hydrosilylations and hydro-cyanations ( 6.3, 6.4, 7.4 and 7.5), cyclopropanations ( 7.19), aldol reactions ( 6.11), allylations of carbanions ( 5.3.2), and some sigmatropic rearrangements ( 10.3). This chapter covers other reactions catalyzed by transition metal complexes including coupling of organometallic reagents with vinyl, aryl or allyl derivatives, Heck reactions allylamine isomerizations, some allylation reactions, car-bene insertions into C-H bonds and Pauson-Khand reactions. 

From Unsaturated Sugars. — Allylic rearrangement of ally cyanates, formed in situ from carbamates such as 24 (derived originally from o-glucal triacetate), yielded isocyanates, e.g. 25, that could then be converted to allylic amine derivatives, e.g. 26 (Scheme 6). Trapping of an allylic... 

A [3,3]-sigmatropic cyanate-isocyanate rearrangement has been identified as a route to a-isocyanato allylboronic esters that can be trapped with nucleophiles (Scheme 2). A DFT (density functional theory) investigation of [3,3]-sigmatropic rearrangement versus a [2 4-2]-cycloaddition of a formal 5 2 substitution of imido metal complexes with allylic electrophiles has been reported (Scheme 3). ... 

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