Iodine(V)-Based Oxidants in Oxidation Reactions

Abstract

The chemistry of hypervalent iodine reagents has now become quite valuable due to the reactivity of these compounds under mild reaction conditions and their resemblance in chemical properties to transition metals. The environmentally friendly nature of these reagents makes them suitable for Green Chemistry. Reagents with a dual nature, such as iodine(III) reagents, are capable electrophiles, while iodine(V) reagents are known for their strong oxidant behavior. Various iodine(V) reagents including IBX and DMP have been used as oxidants in organic synthesis either in stoichiometric or in catalytic amounts. In this review article, we describe various oxidation reactions induced by iodine(V) reagents reported in the past decade.

Keywords: catalyst; hypervalent iodine(V) reagents; oxidant; oxidation.

Figure 1

Hypervalent iodine(V) reagents 1−10.

Scheme 1

Oxidation of alcohols 11 to carbonyl compounds 15 and 16 using iodo-acids 12–14 as precatalysts in the presence of Oxone.

Scheme 2

Catalytic cycle for the oxidation of alcohols 11 to carbonyl compounds 15 using the iodo-acids 14 as precatalysts in the presence of Oxone.

Scheme 3

Oxidation of alcohols 11 to carbonyl compounds 15 using solid-supported iodoarenes 17 and 18 in the presence of a terminal oxidant.

Scheme 4

Oxidation of α-hydroxyphosphonates 19 to α-ketophosphonates 20 using DMP 8 as an oxidant.

Scheme 5

Oxidation of unactivated amines 21 to imines 22 and 2-substituted pyrrolidines 25/26 using IBX 1 as an oxidant.

Scheme 6

Synthesis of quinazolines 29 and 3,4-dihydroquinazolines 30 from o-aminobenzylamine 27 with aldehydes 28 using IBX 1 as an oxidant.

Scheme 7

Plausible mechanism for the synthesis of quinazolines 28 and 3,4-dihydroquinazolines 30 using IBX 1 as an oxidant.

Scheme 8

Oxidation of primary amines 34 to imines 35 using IBX 1 as an oxidant.

Scheme 9

Oxidative addition of isocyanides 36 to the cyclic amines 38 to yield imino-carboxamides 39 using IBX 1 as an oxidant.

Scheme 10

The proposed mechanism for the synthesis of imino-carboxamides 39 using IBX 1 as an oxidant.

Scheme 11

Oxidative cleavage of aryl C−N bonds in N-aryl amides 46 to yield primary amides 48 using IBX 1 as an oxidant.

Scheme 12

Oxidative cleavage of 8-aminoquinoline in N-quinolyl carboxamides 49 to yield primary amides 50 using IBX 1 as an oxidant.

Scheme 13

Oxidative cleavage of alkenes 51 or 52 into ketones 54/carboxylic acids 53 using TetMe-IA 12 as a precatalyst in the presence of Oxone.

Scheme 14

Pd(II)-catalyzed Wacker-type oxidation of alkenes 56 and 58 to ketones 57 using DMP 8 as an oxidant.

Scheme 15

Oxidation of indoles 59 and 3-iodoindoles 61 to isatins 60 using IBX 1 as an oxidant.

Scheme 16

Oxidation of pyrenes 62 to diones 64–66 using IBX 1 as an oxidant.

Scheme 17

Oxidative functionalization of tyrosine 67 to L-DOPA-peptidomimetics 69 using IBX 1 as an oxidant.

Scheme 18

Oxidation of coumarins 72 and 74 to catechols 73 and pyrogallol derivatives 75 using IBX 1 as an oxidant.

Scheme 19

Azidation of 1,3-dicarbonyl compounds 76 to the azide products 78 and 79 using iodine(V) reagent 77 in combination with NaI.

Scheme 20

C−H arylation of naphthoquinones 80 using arylhydrazines 81 as an aryl source and IBX 1 as an oxidant.

Scheme 21

A proposed mechanism for the IBX-mediated C−H arylation of naphthoquinones 80 using arylhydrazines 81 as an aryl source.

Scheme 22

Enantioselective β-C−H functionalization of simple ketones 89 using IBX 1 as an oxidant.

Scheme 23

Oxidative cyclization of hydrazide-hydrazones 95 to α-keto-1,3,4-oxadiazoles 96 and α-keto-1,2,4-triazolo [4,3-a]pyridines 99 using IBX 1 as an oxidant.

Scheme 24

Oxidative coupling of 3-arylprop-2-en-1-ols 100 to yield chiral tetrahydroquinolines 102 using IBX 1 as an oxidant.

Scheme 25

IBX-mediated synthesis of N-PMP-1,2-dihydropyridines (DHPs) 106 via the proline-catalyzed [4 + 2] cycloaddition of glutaraldehyde 103 with aldimines 104.

Scheme 26

IBX-mediated synthesis of pyrrole-2,4-dialdehydes 107 by reacting glutaraldehyde 103 with N-(4-methoxyphenyl)aldimines 104 using proline as a catalyst.

Scheme 27

IBX-mediated synthesis of N-arylpyrrole-3-carbaldehydes 107 from in situ generated aldimines 104 and succinaldehyde 110 using proline as a catalyst.

Scheme 28

Proposed reaction mechanism for the IBX-mediated one-pot synthesis of N-arylpyrrole-3-carbaldehydes 107 using proline as a catalyst.

Scheme 29

IBX-mediated synthesis of 1,4-oxazepines-fused 1,2-dihydropyridines 116 from glutaraldehyde 103 and cyclic imines 115.

Scheme 30

Oxidative cyclization of the Mannich precursors 117 to imidazo [1,2-a]-fused heterobicyclic scaffolds 119 using IBX 1 as an oxidant.

Scheme 31

The plausible mechanism for the oxidative cyclization of the Mannich precursors 117 using IBX 1 as an oxidant.

Scheme 32

Tandem oxidation–cyclization of tryptophan analogs 127 to yield polycyclic spiroindolines 128 using IBX 1 as an oxidant.

Scheme 33

The proposed mechanism for the tandem oxidation–cyclization of tryptophan analogs 127 using IBX 1 as an oxidant.

Scheme 34

Oxidative cyclization of N-hydroxyethyl enamines 133 to yield 2,3-disubstituted pyrroles 135 and pyridines 136 using IBX 1 as an oxidant.

Scheme 35

Oxidative cyclization of α-indolylhydrazones 137 to yield azacarbolines 138 using PhIO₂ 9 as an oxidant.

Scheme 36

Tentative mechanism for the oxidative cyclization of α-indolylhydrazones 137 using PhIO₂ 9 as an oxidant.

Scheme 37

IBX–I₂-mediated synthesis of β-carbonyl sulfones via the deacylative sulfonylation of 1,3-dicarbonyl compounds.