Iodo isocyanate

March82 has summerized the addition reactions of iodine isocyanate (IN=C=0) to C=C functions which were reported in the period 1963-1983. These reactions are similar to those with iodine azide described above. With IN=C=0, p-iodo isocyanates are formed (equation 55). As is the case with IN3, the addition is stereospecific and anti. The... 

J-Iodo isocyanates were obtained by addition of iodine isocyanate or thiocyanate to al-kenes45 61. Iodine isocyanate is generated by adding iodine to a suspension of silver cyanate in diethyl ether at — 15°C. When an alkene is present in the reaction medium, anti addition takes place and /J-iodo isocyanates result in good yield52. 

The reaction proceeds with total regio- and diastereoselectivity, as shown by H-NMR spectroscopy. /J-Iodo isocyanates are generally unstable, their purification is difficult and it is convenient to convert them into more stable derivatives. /Hodo carbamates were readily and stereose-lectively prepared by warming the isocyanate with an appropriate alcohol and successive thermal nucleophilic displacement yielding 2-oxazolidinones, e.g., 19 - 20 (see Table 3). Furthermore, when trans-iodo isocyanates were treated with an alcohol in basic medium, the carbamates form first and were immediately converted into the corresponding aziridines, e.g, 19 -> 21. 

Iodine isocyanate, IN=C=0. Mol. wt. 168.93. Preparation from silver cyanate and iodine. The reagent adds to olefins in the trans manner to give iodo-isocyanates," of interest because they can be transformed into ethyleneimines." The reaction is... 

Hassner et aU have discussed in detail the procedure and scope of the addition to olefins. Lithium or sodium methoxide is recommended as catalyst for conversion of the iodo isocyanate to the carbonate. If the end product desired is the aziridinc it is usually advantageous to convert the iodo isocyanate into the sodium bisulfite adduct which is convertible by base into the aziridine. 

Cayli, G., Kiisefoglu, S. (2010). A simple one-step synthesis and polymerization of plant oil triglyceride iodo isocyanates, J. AppL Polym. Set, 116, 2433-2440. 

Soybean oil iodo isocyanate was synthesised by reacting the pristine oil with iodo isocyanate (Scheme 4.13a) to yield a degree of triglyceride substitution of 3 [47], The same oil was treated with N-bromosuccinimide at the allylic positions of each of its fatty-acid chains, followed by reaction with silver isocyanate (AgNCO) (Scheme 4.13b) to prepare the desired multi-isocyanate in which <70 % of bromine atoms were converted into NCO groups [48]. 

Iodine isocyanate was used to synthesize the first steroidal aziridine, 2, 3 -iminocholestane (95). from 5a-cholest-2-ene (91). This reaction sequence which is believed to proceed through a three-membered ring iodonium ion (92) illustrates the limitation of pseudohalogen additions for the synthesis of -aziridines. The iodonium complex forms from the least hindered side (usually alpha) and is opened tmK5-diaxially to give a -oriented nitrogen function. The 3a-iodo-2 -isocyanate (93) is converted by treatment with... 

Iodine azide, on the other hand, forms pure adducts with A -, A - and A -steroids by a mechanism analogous to that proposed for iodine isocyanate additions. Reduction of such adducts can lead to aziridines. However, most reducing agents effect elimination of the elements of iodine azide from the /mwj -diaxial adducts of the A - and A -olefins rather than reduction of the azide function to the iodo amine. Thus, this sequence appears to be of little value for the synthesis of A-, B- or C-ring aziridines. It is worthy to note that based on experience with nonsteroidal systems the application of electrophilic reducing agents such as diborane or lithium aluminum hydride-aluminum chloride may yet prove effective for the desired reduction. Lithium aluminum hydride accomplishes aziridine formation from the A -adducts, Le., 16 -azido-17a-iodoandrostanes (97) in a one-step reaction. The scope of this addition has been considerably enhanced by the recent... 

The Synthesis of 2, 3 -/mino-5acho/estane via the 3a-iodo-2 -isocyanate ... 

The 3a-iodo-2]5-aminocholestane hydroiodide (94) is made by treating a solution of the above isocyanate (0.5 g) in 50 ml of acetone with 10 ml of 50% hydroiodic acid at room temperature for 1.5 hr. The addition of 50 ml water then precipitates the hydroiodide which may be filtered off and dried 0.56 g mp 197-198° (block preheated to 180°). 

Iodine isocyanate, 22 1,5-Iodohydrin formation, 252 21-Iodo-3 -Hydroxypregn-5-en-20-one acetate, 208 W-iodosuccinimide, 209 Isohexylmagnesium bromide, 68... 

Iodine isocyanate, 0524 Iodine(V) oxide, 4627 Iodine(VII) oxide, 4628 Iodine pentafluoride, 4355 Iodine(III) perchlorate, 4140 Iodine triacetate, 2394 lodobenzene, 2249 4-Iodo-3,5-dimethylisoxazole, 1868 lododisilane, 4543 2(2-Iodoethyl)-l,3-dioxolane, 1928 l-Iodohexa-2,4-diene, 2393... 

In a related organometallic approach, treatment of the diiodoarylformamidine 878 with isopropylmagnesium bromide gave an organomagnesium intermediate which reacted with a variety of alkyl, allyl, and aryl isocyanates to give 3-substituted-8-iodo-4(37/)-quinazolinones 879 <20020L1819>. 

Amines have been prepared on insoluble supports by Hofmann degradation of amides [222] followed by hydrolysis of the intermediate isocyanates (Figure 10.5). One reagent suitable for this purpose is [bis(trifluoroacetoxy)iodo]benzene, which can be used both on cross-linked polystyrene [223] and on more hydrophilic supports such as polyacrylamides (Figure 10.6). Support-bound carboxylic acids can also be degraded via the acyl azides (Curtius degradation [224,225]) to yield isocyanates. 

The Lewis acid-catalysed 3 + 2-cycloaddition of aziridine-2-carboxylates with isocyanates proceeds regio- and stereo-specifically to produce enantiomerically pure 4-substituted imidazolin-2-ones in high yields.33 The reaction of ethyl 7-iodo-2-heptynoate (27), 2-arylaziridines (28), and K2C03 produces polysubstituted indolizidines (30) via an S /formal 3 + 2-cycloaddition (29) process (Scheme 8).34... 

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