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.

Synergy Effects in the Chemical Synthesis and Extensions of Multicomponent Reactions (MCRs)—The Low Energy Way to Ultra-Short Syntheses of Tailor-Made Molecules

“…[31] gave access to a versatile and broad range of prospective syntheses. MCR chemistry has seen a very fast upswing (over 500 reviews) since the turn of the millennium, while the number of new MCRs and their application is increasing steadily, demonstrated in some reviews [32][33][34][35][36][37][38][39][40][41].…”

“…IMCRs [38,42 -50], alkyne-based [38,[51][52][53][54] and C-H-acidic compounds [55][56][57][58][59][60] based MCRs in particular have a high potential to be very diverse. Many noval MCRs [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] have meanwhile become part of the range of syntheses, e.g.…”

“…MCRs have been also applied in polymer [74], nucleoside [75] and carbohydrate [76] chemistry. Main field of application remains the production of heterocyclic compounds and many natural products by means of MCR [38,[77][78][79][80][81][82][83][84][85][86][87][88][89], leading directly towards drug design and discovery [90][91][92][93][94]. Scheme 9 presents a current brief of well-known multicomponent reactions [35,40,9,[95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110].…”

“…Various forms of the energy can be transmitted by excitation of certain bonds such as carbonyl or hydroxy and amino functional groups via: Microwaves (MW) [38,[152][153][154][155], infrared (IR) [156] and ultrasound (US) [38,157]. They can cause rather substantial effects on the MCRs.…”

“…This is different from the orthogonal highly active functional isocyanate group (strong electrophile) and isocyanide (strong nucleophile) which within one molecule I-I (isocyanatoisocyanide) are both looking for suitable partners for the MFCR (multifunctional component reaction). For the nomenclature of the MFCR refer to [38,39]. Scheme 17 introduces the I-I 19, which is produced from formamido-amine by means of phosgene.…”