Iodane, Amino

Reactions of chiral A, -iodanes, amino acid-derived benziodazole oxides 58 [76], (5)-proline based reagents 59 [77], and iodylarenes 60 bearing ester motives [78] with non-symmetric sulfides to give asymmetric sulfoxide formation further recognized the importance of such transformations. 

Oxidation of primary N-aminobenzimidazole 32 with PhI(OAc)2 4 in the presence of olefins gives aziridines 34 [54]. Similar oxidations are effected by lead tetraacetate. The reaction was initially proposed to involve the intermediacy of AT-nitrene as a reactive species, thought to be produced through reductive a-elimination of amino-A3-iodane 33. Recent mechanistic studies on lead tetraacetate oxidation, however, suggests that the acetoxyamine 35 instead of AT-nitrene is the aziridinating species, and the reaction proceeds through a transition state 36 similar to that of epoxidation using peracids [55]. 

Macrocyclic hypervalent iodine trimer 145 was prepared directly from the oxidation of amino acid 143 [Eq. (117)] [226] self-assembly of the monomeric A3-iodane 144 directed by secondary bonding between iodine and oxygen atom of the amino acid fragment is responsible for the formation of the trimer 145, in which iodine atoms have the pentagonal planar geometry. 

Oxidation of the N-(iodobenzoyl) derivatives of some a-amino acids gave interesting results with dimethyldioxirane at 0°C non-isolable monomeric tricyclic products were apparently formed which underwent spontaneous self-assembly to afford trimeric macrocycles [81]. The same substrates, either with oxone in water at 70 °C or with KBr03/H2S04 were converted to the monomeric tricyclic A5-iodanes (Scheme 30) [82]. 

A major advance was accomplished with the introduction of hydrazine derivatives by Che, in particular, M-amino phthalimide [38]. Although initial work had relied on PhI(OAc)2 as the oxidant, the same group later discovered that a tricomponent system consisting of 2-iodoanisole (49), wCPBA, and the A -amino phthalimide could be employed for an in situ preparation of the required imino-iodane [39]. It is important to note that the final iminoiodane contains a 2-methoxyphenyl substituent, which is in line with the observation from Zhdankin on enhanced solubility of derivatives of the type 42. Under these conditions, a series of styrenes 48 could be submitted to intermolecular aziridination and provided products 50 under mild conditions and in good to excellent yields. 

The Hofmann-type rearrangement of aromatic and aliphatic imides using KBr as the catalyst gives aromatic and aliphatic amino acid derivatives. Using a hypervalent iodine(III) reagent generated in situ, amino acid derivatives are formed via alcoholysis followed by a Hofmann rearrangement promoted by the formation of an imide-A -iodane intermediate (Scheme 170). ... 

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