6. New Synthetic Building Blocks
6.1 Domino Reactions of 2-Isothiocyanatobenzonitrile
Abstract: 2-Isothiocyanatobenzonitrile (ITCB) and isocyanatobenzonitrile (ICB) represent versatile synthetic building blocks containing a nitrile and an isothiocyanate or an isocyanate function, respectively. Domino reactions of ITCB and ICB provide a convenient access to a variety of pharmacologically important heterocycles.
Review: Curr. Org. Chem. 2009, 13, 955-964.
Period of investigation: 2002 – 2009
Keywords: domino reactions; cyclizations; heterocycles
6.2 Cyclizations of 1,1-Diacylcyclopropanes
Abstract: The cyclization of 1,1-diacylcyclopropanes with free and masked dianions provides spirocyclopropanes which readily undergo ring-cleavage reactions. Cyclopropylated 1,3,5-tricarbonyl compounds were prepared for the first time. Based on this work also other syntheses of cyclopropanes were developed.
Review: Synlett 2023, 34, 1765-1776.
Period of investigation: 2002 - 2011
Keywords: cyclopropanes; cyclizations; dianions; 1,3-dicarbonyl compounds
6.3 Cyclizations of Bis-Imidoylchlorides of Oxalic Acid
Abstract: The cyclization of oxaldiimidoyl dichlorides, readily available novel building blocks, with ambident dianions and other bis(nucleophiles), such as diamines, provides a convenient access to a variety of heterocycles important in medicinal chemistry or materials science. Reactions include cyclization-, domino-, one-pot- and double-anion-capture-reactions.
Review: Eur. J. Org. Chem. 2002, 221-234.
Period of investigation: 1999 – 2006
Keywords: cyclizations; dianions; heterocycles
6.4 Cyclizations of (2,4-Dioxobutylidene)phosphoranes
Abstract: (2,4-Dioxobutylidene)phosphoranes can be regarded as equivalents of 1,3-dicarbonyl dianions and represent versatile building blocks in one-pot cyclizations. Their reactions with various electrophiles, such as 1,3-dicarbonyl compounds, enones, a-halo ketones, or hydrazine derivatives, allow for a convenient synthesis of a variety of carbo- and heterocyclic ring systems.
Review: Synthesis 2008, 3877-3902.
Period of investigation: 2000 – 2007
Keywords: 1,3-dicarbonyl compounds; cyclizations; heterocycles; arenes