112183-09-2Relevant academic research and scientific papers
Two Regiocomplementary Approaches to Angular Furanocoumarins with Chromium Carbene Complexes: Synthesis of Sphondin, Thiosphondin, Heratomin, and Angelicin
Wulff, William D.,McCallum, J. Stuart,Kunng, Fen-Ann
, p. 7419 - 7434 (2007/10/02)
Two regiocomplementary syntheses of the angular furanocoumarin sphondin are described utilizing the benzannulation reaction of furylcarbene complexes of chromium.The high regioselectivity of an intermolecular synthesis employing the reaction of pentacarbonylchromium (8) and methyl 4-pentynoate is thought to be controlled by the preferred conformation of an alkyne-carbene complex intermediate.By utilizing the same acetylene, heratomin and an unnatural derivative of sphondin, 6-methoxy-2-oxo(2H)-thiofuro(2,3-h)benzopyran were prepared from pentacarbonylchromium (37) and pentacarbonylchromium (31), respectively.An intramolecular synthesis of sphondin from oxy>carbene>pentacarbonylchromium (10e) incorporates the acetylene with reversed regiochemistry due to the geometrical constraints of the intramolecular annulation.Control over the formation of the regiochemistry correct for the carbon skeleton of sphondin is possible due to the regioselectivity in the annulation of unsymmetrical aromatic substituents (3-furyl) on the carbene carbon.The intramolecular synthesis is thus related to the intermolecular synthesis by a double reversal in the regiochemistry.A convergent synthesis of sphondin and angelicin is described which has the phenol 72 produced from the intramolecular benzannulation of complex 10e as a branch point and is differentiated by whether the phenol functionality is retained or reduced.
PALLADIUM CATALYZED REDUCTION OF ARYL TRIFLATES - UTILIZATION IN THE SYNTHESIS OF ANGELICIN, OLIVIN AND CHROMOMYCINONE FROM PHENOLS PRODUCED IN THE BENZANNULATION REACTION OF CHROMIUM CARBENE COMPLEXES
Peterson, Glen A.,Kunng, Fen-Ann,McCallum, Stuart J.,Wulff, William D.
, p. 1381 - 1384 (2007/10/02)
The palladium catalyzed homogeneous reduction of a variety of phenols with either sodium borohydride or triethylammonium formate are effected as their triflate esters.This transformation extends the usefullness of the benzannulation reaction of chromium carbene complexes with acetylenes and is exemplified for the synthetic targets angelicin, olivin, and chromomycinone.
