NATURAL PRODUCT SYNTHESIS VIA THE POLYBROMO KETONE-IRON CARBONYL REACTION

Article abstract of DOI:10.1016/S0040-4020(01)91427-9

Application of the polybromo ketone-iron carbonyl reaction to natural product synthesis is summarized.The general synthesis of tropane alkaloids has been achieved via the reductive <3+4> cyclocoupling of sym-tetrabromoacetone with N-methoxycarbonylpyrrole as the key step.Ready availability of 8-oxabicyclo<3.2.1>oct-6-en-3-one from the tetrabromoacetone and furan has opened a new, efficient entry to natural C-nucleosides including pseudouridine, pseudocytidine, and showdomycin.The artificial analogues such as 2-thiopseudouridine, 6-azapseudouridine, pseudoisocytidine, etc., are also obtainable.The oxabicyclic ketones bearing an isopropyl substituent at the appropriate position serve as intermediates for the synthesis of naturally occurring troponoids, nezukone, α-thujaplicin, and hinokitiol (β-thujaplicin).Carbocamphenilone and camphenic acid have been prepared through the <3+4> reaction of 1,1,3-tribromo-3-methylbutan-2-one and cyclopentadiene.The <3+2> cyclocondensation of α,α'-dibromo ketone and a styrene derivative leads to the single-step synthesis of α-cuparenone. 1,3-Dibromo-3,7-dimethyloct-6-en-2-one derived from nerol (or geraniol) undergoes the biogenetic-type double cyclization.The iron carbonyl-assisted intramolecular <3+2> cyclocoupling gives camphor accompanied by other monoterpenic ketones.A mixture of campherenone and epicampherenone has been obtained from related dibromo ketone prepared from farnesols.The hetero <3+2> reaction by use of dibromo ketones and N,N-dimethylcarboxamides, forming 3 (2H)-furanones, is employable for the preparation of muscarine alkaloid derivatives.