Iodine isocyanate addition reactions

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... 

Iodine isocyanate additions result in approximately 40% yields. The products can undergo typical reactions of the isocyanate group/ as above, and also ... 

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... 

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. 

This stereochemical character is shared by all addition reactions involving a halonium ion, so that mixed halogens e.g. Br-F [8g], Br Cl [go], I Cl [gi] and I F [g2]), and also reagents like hypobromous acid (Br-OH) [gs], acetyl hypobromite (CH3CO OBr) [g4] and iodine isocyanate (I NCO) [gs] lead to diaxial addition products, with the... 

Episulfides. Hinshaw reasoned that addition of an alkene to such solutions should give jS-iodothiocyanates in analogy with the reaction of iodine isocyanate (1, 501 2, 223-224 . 3, 161 -16.3) with alkenes. indeed treatment of cyclohexene with iodine thiocyanate gives a /5-iodothiocyanate (2), which on treatment with methanolic... 

Addition to alkenes. The addition reaction of iodine isocyanate to alkenes is much faster in methylene chloride than in ether, the commonly used solvent. The... 

Kumar and coworkers have reported preparation of 2, 3 -epimino analogues of the antibiotics neamine, ribostamine, and kanamycin B by reaction of suitably protected vicinal benzyloxycarbonylamino tosylates with NaH in N,N-dimethylformamide, followed by deprotection. lodo-carbamates 119 and 120 were obtained by addition of iodine isocyanate to 2-methoxy-4,6-dimethyl-3, 6-dihydro-2/f-pyrane 118 (a mixture of cis and trans isomers), followed by treatment with MeOH. Treatment of compound 119 and 120 with potassium hydroxide in refluxing methanol afforded epimines 121 and 122. 

Figure 22.8 Schematic reaction for addition of iodine isocyanate to plant oil triglycerides (reprinted with permission of Cayli and Kiisefoglu, 2010, John Wiley and Sons [35]].

Thus, for the addition of the hypohalous acids (Table 6.1, entry 9, HOX X = Cl, Br, I) the halogen adds as X+, forming the expected halonium ion and this is attacked by HO (or its equivalent) as shown in Scheme 6.22. The same process obtains for the addition reactions of nitrosyl chloride (NOCl), iodine azide (IN3), and iodine isocyanate (INCO) (Thble 6.1, entries 11,12, and 13, respectively) where the more... 

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