Diversity oriented syntheses of conventional heterocycles by smart multi component reactions (MCRs) of the last decade

Abstract

A collection of smart multicomponent reactions (MCRs) with continuative post condensation cyclizations (PCCs) is presented to construct conventional three- to seven-membered heterocyclic compounds in diversity oriented syntheses (DOS). These will provide a high degree of applying economical and ecological advantages as well as of practicability. Water, ionic liquids, and solvent-less syntheses as well as use of various forms of energy as microwave and ultrasonic irradiation are examined and discussed.

Scheme 1

Indole syntheses (1)–(3) under various reaction conditions.

Scheme 2

Synthesis of aziridine 3 by U-5F4CR.

Scheme 3

Synthesis of azetidinone 4 by U-4F3CR.

Scheme 4

Synthesis of azetidine 6 by 3CR.

Scheme 5

Synthesis of pyrrole 7 by H-4F3CR.

Scheme 6

Synthesis of pyrrole 9 by H-3CR.

Scheme 7

Synthesis of pyrrolidine 11 by I-4CR.

Scheme 8

Synthesis of amino-furan 13 by I-3CR.

Scheme 9

Synthesis of indole 15 by Corey-Chaykovsky 3CR.

Scheme 10

Synthesis of pyrazol 17 by I-3CR.

Scheme 11

Synthesis of pyrazoline 19 by 3CR/PCC.

Scheme 12

Synthesis of imidazole 21 by U-5F4CR/PCC.

Scheme 13

Synthesis of imidazolium salt 25 by I-3CR.

Scheme 14

Synthesis of oxazolidinone 27 by 3CR.

Scheme 15

Synthesis of thiazole 30 by U-4CR/PCC.

Scheme 16

Synthesis of oxazino-1,2,3-triazole 33 by P-5F3CR/PCC.

Scheme 17

Synthesis of 1,2,4-triazolidine 35 by 3CR.

Scheme 18

Synthesis of tetrazole 37 by 3CR.

Scheme 19

Synthesis of tetrazolyl isoindoline 40 by U-5F4CR.

Scheme 20

Synthesis of pyridine 45 by U-5F4CR.

Scheme 21

Synthesis of pyrane 47 by I-3CR/PCC.

Scheme 22

Synthesis of isoquinoline 50 by 5F4CR.

Scheme 23

Synthesis of pyridopyrimidine 52 by I-4F3CR.

Scheme 24

Synthesis of piperazine 55 by U-4F3CR.

Scheme 25

Synthesis of tetrazinane 57 by 3CR.

Scheme 26

Synthesis of oxadiazepine 59 by U-6F4CR/PCC.

Scheme 27

Synthesis of oxadiazepine 62 by I-3CR.

Scheme 28

Isocyanate 63 formation as by-product in a pyrrole synthesis.

Scheme 29

Ketene 68 formation as by-product in a pyridine synthesis.

Scheme 30

Resonance effect of isocyanide 69.

Scheme 31

Generation of isocyanides from formamides.

Scheme 32

Generation of isocyanides from 1,3-oxazoles.

Figure 1

Strategies and tools to design DOS for complex heterocycles by MCRs.