Isocyanates, trichloroacetyl

Phosgene reacts exothermically with thiirane in two steps (Scheme 36) (77MI50602). 3,5-Dinitrobenzoyl chloride and benzoyl fluoride initiate polymerization of thiirane. A novel reaction of benzoyl isocyanate or trichloroacetyl isocyanate, which yields ethylenethiol derivatives from epithiochlorohydrin (2-chloromethylthiirane), 2-methylthiirane or cyclohexene episulfide, has been reported (Scheme 37) (71BAU2432). 

The ease with which furans react with electrophiles is forcibly demonstrated by the reaction (in CHC13 at 25°C) of 2,4-dimethylfuran with trichloroacetyl isocyanate to give the amide 56a.129 Attack at the 3-position is not easy, but still the azide of 3-(2-furyl)propenoic acid at 230°C gives an isocyanate that... 

Nucleophilic olefins react readily with trichloroacetyl isocyanate to give l,3-oxazin-4-ones. In this way, norbornadiene 188 yields the 5,8-methano-2//-l,3-benzoxazin-4-one 189 (69JOC633). A similar 1,4-addition starting... 

Stable arylnitrile oxides undergo cycloaddition to the G=N bond of chlorocarbonyl isocyanate to give compounds (185) <90ZOR339>. In contrast, cycloaddition of nitrile oxides to trichloroacetyl isocyanate occurs across the C=0 double bond leaving the isocyanate group unaffected. From... 

The synthesis of the protected 5-hydroxy P-amino acids 91 required a stereoselective amination of the vinyl sulfoximine 4 (Scheme 1.3.29). Carbamoylation of alcohols 4 with trichloroacetyl isocyanate afforded carbamates 86 in high yields. 

The reaction of methyl (3-hydroxypyridin-2-yl)ketone oxime (487) with thionyl chloride, trichloroacetyl isocyanate or chlorosulfonyl isocyanate gave 3-methylisoxazolo[4,5-6]pyridine (488) in varying yields dependent upon the temperature and solvent (Equation (43)) <87H(26)292l>. Trichloroacetyl isocyanate was particularly effective in the formation of compound (488) in either diethyl ether or tetrahydrofuran, at ambient temperature or at reflux, affording 60-78% yields. The treatment of 2-acetyl-3-hydroxypyridine (489) with hydroxyamine 0-sulfonic acid afforded a 1 1 mixture of compound (488) and 2-methyloxazolo[4,5-6]pyridine (490) (Equation (44)). The formation of the isomer (490) results from a Beckmann rearrangement. 

Dihydro-l,3-oxazin-4-ones 375 are obtained from various enamines 374 and benzoyl isocyanate in contrast, trichloroacetyl isocyanate is reported to give only the azetidinone 376 (equation 154)27. 

Trichloroacetyl isocyanate (82.2 mmol) was added dropwise to a mixture of the Step 2 product (68.5 mmol) dissolved in 300 ml CH2C12, then stirred for 30 minutes. TLC monitoring indicated the presence of Step 2 product, so additional trichloroacetyl isocyanate (4.5 g) was added. After 1 hour, TLC analysis indicated that the reaction was complete and the product was isolated as a pale yellow solid using the Step 2 workup. 

Acyl isocyanates are more reactive than alkyl or aryl isocyanates. However, the presence of an additional rr-bond conjugated to the C>i-N bond of the isocyanate opens the possibility for [4 + 2] cycloadditions to compete with normal [2 + 2] additions. Reactions with alkyl and aryl substituted alkenes are rather slow. Propene, tranj-2-butene, styrene and conjugated dienes give only 3-lactams, albeit in moderate yields (Scheme 25). The strained double bond of norbomene, a reactive dienophile, adds across the conjugated 4iT-system of trichloroacetyl isocyanate (equation 51). 

The use of trichloroacetyl isocyanate to generate carbamates in situ can be used to identify methyl groups adjacent to a tertiary alcohol (downfield shift of 0.29—0.44 p.p.m.) and to assign the geometry of double bonds in allylic alcohols. Similarities in the n.m.r. and infrared spectra of monoterpenoids may be valuable in identifying new sesquiterpenoid analogues. ... 

Nitrosolysis of camphor ethyl acetal with ethanolic ethyl nitrite in sulphur dioxide yields the orthoester oxime (205) which is rapidly dehydrated by excess acetal to the orthoester nitrile which then reacts with sulphur dioxide to form the ester nitrile and diethyl sulphite.Further papers in this section include the full paper on ozonolysis of silyl ethers (Vol. 5, p. 33), another synthesis of camphor-enol trimethylsilyl ether (cf. Vol. 6, p. 41)/°° the conversion of camphor oxime with Grignard reagents into the corresponding imine with no aziridine formation/° the preparation of (206) by treating bornylene with trichloroacetyl isocyanate/ the oxidation of thiocam-phor to the 5-oxide and alkylation in the presence of thallium(i) ethoxide to a/S-unsaturated sulphoxides/ and the free-radical C-3 alkylation of camphor with alkenes. " ... 

A. Dondoni, A. Marra, and A. Massi, Hybrid solution/solid-phase synthesis of oligosaccharides by using trichloroacetyl isocyanate as sequestration-enabling reagent of sugar alcohols, Angew. Chem. Int. Ed., 44 (2005) 1672-1676. 

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. ... 

Synthesis from o-allose A synthesis of the (3-lactam 15 has been reported from the D-allose derivative 11 (Scheme 1). Silylation of 11 followed by treatment with trichloroacetyl isocyanate afforded after crystallization the (3-lactam 12 (50%). Benzylation of 12 afforded 13, which underwent removal of the protecting groups to give 14. Cleavage of the vicinal diol group in 14, with sodium metaperiodate under standard conditions, led to the formation of a dialdehyde, which without isolation was reduced to give the (3-lactam derivative 15. 

The reaction of hydroxylated compounds (alcohols or phenols) and amines with trichloroacetyl isocyanate (TAI) (47) to form urethanes and ureas, respectively (48), can be performed within the NMR tube. This method, however, is restricted to compounds containing those functionalities and has not been applied widely. 

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