Catalytic One-Pot Diastereoselective Michael-Initiated Ring-Closure of Methyl Ketones with 3-Bromochromones: Synthesis of Cyclopropa[b]chromanones

authors	Sousa, JLC; Talhi, O; Mendes, RF; Paz, FAA; Bachari, K; Silva, AMS
nationality	International
journal	EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
author keywords	Oxygen heterocycles; Cyclopropanes; Small ring systems; Fused-ring systems; Michael addition; Cyclization
keywords	1,2,3-TRISUBSTITUTED CYCLOPROPANES; NATURAL-PRODUCTS; MIRC REACTIONS; DISCOVERY; ANALOGS; AGENTS
abstract	A one-pot diastereoselective base-catalyzed Michael-initiated ring-closure (MIRC) of activated methyl ketones with 3-bromochromones to give cyclopropa[b]chromanones is described. Three asymmetric centres are generated in the new cyclopropa[b]chromanone skeleton. Stereochemistry studies based on NMR spectroscopy and single-crystal X-ray diffraction analysis revealed the trans configuration of the cyclopropane ring, with the (1R,1aS,7aR)/(1S,1aR,7aS) pair of enantiomers, as was further confirmed by chiral HPLC. The use of acetone in our reaction produced a 1-acetyl-substituted cyclopropa[b]chromanone that can undergo a subsequent MIRC reaction with a second molecule of 3-bromochromone to give the first described 1,1-carbonylbis(cyclopropa[b]chromanone) dimers as a meso form.
publisher	WILEY-V C H VERLAG GMBH
issn	1434-193X
year published	2016
issue	23
beginning page	3949
ending page	3958
digital object identifier (doi)	10.1002/ejoc.201600413
web of science category	Chemistry, Organic
subject category	Chemistry
unique article identifier	WOS:000382962700006