Isocyanates, rearrangements give

Rearrangement polymerisation Here the mechanism resembles condensation polymerisation hut no stnall mbleculfr is split out. In the first example l 4-butane di6l reacts with hexaniethyiehe di-isocyanate to give 6,4-poly-... 

Examples of the reaction of tervalent phosphorus with isocyanates and their analogues include the addition of phosphites to carbonyl isothio- and isoseleno-cyanates to give the phosphonates (32) and the reaction of dialkyl phosphoramidites with trichloroacetyl isocyanate to give the rearranged product (33). Predictably, the betaine (34) is obtained from the reaction of TDAP with fluorosulphonyl isocyanate more surprising is the relative stability of (34) to hydrolysis. ... 

Oxazepam (116) can be converted into a range of 3-(disubstituted-amino) derivatives, in moderate yield, by its reaction with the appropriate 2-amino-4,5-dihydro-l,3,2-dioxaphosphole. A direct route to the 3-amino-derivatives has also been reported.l,3-Dihydro-2//-l,4-benzodiazepin-2-ones react with most isocyanates to give the 1-carbamoyl derivative however, (114), on reaction with trichloroacetyl isocyanate and subsequent hydrolysis, gave the 3-amido-derivative. The latter has been converted into a range of 3-esters.Continuing work on the electrolytic reduction of 2,3-dihydro-l,4-diazepinium salts has shown that the AW-dibenzyl-6-phenyl-compound gives a diazepine dimer and an unexpected rearrangement product, which is 1,4-di-imidazolidinyl-butadiene. ... 

Kinetic studies of the reactions between cis-bicyclo[6,l,0]-nona-2,4,6-triene and tetracyanoethylene or halogenosulphonyl isocyanates, which give the rearranged adducts (180) and (181), respectively, are inconsistent with the mechanisms suggested previously. Other mechanisms are suggested which involve a Cope rearrangement of... 

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]. 

I have also included in this book the insertion reactions of carbon cumulenes into polarized metal single bonds, which can be perceived as an initial [2+2] cycloaddition, which subsequently rearranges to give a linear adduct. The reactivity of the metal substituent appears to be NR2 > OR > SR. When the metal compound contains several reactive groups, stepwise insertion occurs. For example, Sn(OR)4 reacts with phenyl isocyanate to give the tetracarbamate Sn[N(Ph)COOR]4. Mixed insertion products are obtained using different isocyanates. In the insertion reactions of carbodiimides sometimes ionic cyclic amidinate complexes are formed. 

Several olefins react with chlorosulfonyl isocyanate to give the rearranged linear adducts examples include 1,1-diphenylethylene and trimethylcyclopropene, but from diolefins mono [2+2] cycloadducts are usually formed. 

The insertion of isocyanates into C-H bonds is also well known. Olefins, alkanes, aromatic and heteroaromatic compounds are known to react with isocyanates to give N-substituted carboxylic acid amides. Often the formation of the linear adduct is the result of a [2+2] cycloaddition reaction and subsequent rearrangement. Electron donating groups on the aromatic nucleus on the one side and electron withdrawing groups on the isocyanate enhance the reactivity of both components. Lewis acids, such as aluminum chloride, are supplied successfully as catalysts... 

Both alkyl- and aryl isocyanates insert readily into As-N bonds In contrast, As(NMc2)3 reacts with fluorosulfonyl isocyanate to give a rearrangement product 322. ... 

Carbamoyl isothiocyanates in their reactions with isonitriles afford iminooxazo-linethiones 21 (when R = Me or Et) or they react as the rearranged thiocarbamoyl isocyanates to give iminothiazolinones 22 (when R = CeHn) . 

The thermal rearrangement of carbonyl azides (Curtius rearrangement) giving isocyanates in quantitative yields at 60-80 °C has been known over the years and has been... 

A third approach to 3-amino-/3-lactams is by Curtius rearrangement of the corresponding acyl azides. These are readily prepared from r-butyl carbazides, available via photochemical ring contraction of 3-diazopyrrolidine-2,4-diones in the presence of f-butyl carbazate (c/. Section 5.09.3.3.2). Thus treatment of (201) with trifluoroacetic acid followed by diazotiz-ation gives the acyl azide (202) which, in thermolysis in benzene and subsequent interception of the resulting isocyanate with r-butanol, yields the protected 3-amino-/3-lactam (203) (73JCS(P1)2907). 

An isocyanate 2 formed by a Curtius rearrangement can undergo various subsequent reactions, depending on the reaction conditions. In aqueous solution the isocyanate reacts with water to give a carbaminic acid 6, which immediately decarboxylates to yield an amine 3. When alcohol is used as solvent, the isocyanate reacts to a carbamate 7 ... 

In the Lossen reaction a hydroxamic acid derivative (usually an 0-acyl derivative) is deprotonated by base, and rearranges via migration of the group R to give an isocyanate 2. Under the usual reaction conditions—i.e. aqueous alkaline solution—the isocyanate reacts further to yield the amine 3. The Lossen reaction is closely related to the Hofmann rearrangement and the Curtins reaction. 

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