C07C67/333

PROCESS FOR PREPARATION OF ACITRECIN

The present invention provides a process for preparation of {(2E,4E,6E,8E)-9-(4-methoxy-2,3,6-trimethyl)phenyl-3,7-dimethyl-nona-2,4,6,8}tetraenoate, an acitretin intermediate of formula (VI) with trans isomer≧97%, comprising of reacting 3-formyl-crotonic acid butyl ester of formula (V), substantially free of impurities, with 5-(4-methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene-1-triphenyl phosphonium bromide of formula (IV) and isolating resultant compound of formula (VI), treating the filtrate with iodine for isomerization of the undesired cis intermediate and finally obtaining acitretin (I), with desired trans isomer≧97%.

METAL OXIDE CATALYZED RADIOFLUORINATION

Inter alia, the first titania-catalyzed [.sup.18F]-radiofluorination in highly aqueous medium is provided. In embodiments, the method utilizes titanium dioxide, 1:1 acetonitrile-thexyl alcohol solvent mixture and tetrabutylammonium bicarbonate as a base. Radiolabeling may be directly performed with aqueous [.sup.18F]fluoride without the need for drying/azeotroping step, which reduces radiosynthesis time while keeping high fluoride conversion. The general applicability of the synthetic strategy to the synthesis of the wide range of PET probes from tosylated precursors is demonstrated.

METAL OXIDE CATALYZED RADIOFLUORINATION

Inter alia, the first titania-catalyzed [.sup.18F]-radiofluorination in highly aqueous medium is provided. In embodiments, the method utilizes titanium dioxide, 1:1 acetonitrile-thexyl alcohol solvent mixture and tetrabutylammonium bicarbonate as a base. Radiolabeling may be directly performed with aqueous [.sup.18F]fluoride without the need for drying/azeotroping step, which reduces radiosynthesis time while keeping high fluoride conversion. The general applicability of the synthetic strategy to the synthesis of the wide range of PET probes from tosylated precursors is demonstrated.

Sulfur chelated ruthenium compounds useful as olefin metathesis catalysts

Sulfur chelated ruthenium compounds represented by the following formula: ##STR00001##
wherein M indicates the ruthenium metal bound to a benzylidene carbon; R represents C.sub.1-C.sub.7 alkyl group or optionally substituted aryl; X.sub.1 and X.sub.2 each independently represent halogen; Y.sub.1 and Y.sub.2 each independently denote unsubstituted or alkyl-substituted phenyl; and Z independently represents hydrogen, electron withdrawing or electron donating substituent, with m being an integer from 1 to 4, and processes and compositions related thereto.

Sulfur chelated ruthenium compounds useful as olefin metathesis catalysts

Sulfur chelated ruthenium compounds represented by the following formula: ##STR00001##
wherein M indicates the ruthenium metal bound to a benzylidene carbon; R represents C.sub.1-C.sub.7 alkyl group or optionally substituted aryl; X.sub.1 and X.sub.2 each independently represent halogen; Y.sub.1 and Y.sub.2 each independently denote unsubstituted or alkyl-substituted phenyl; and Z independently represents hydrogen, electron withdrawing or electron donating substituent, with m being an integer from 1 to 4, and processes and compositions related thereto.

Sulfur chelated ruthenium compounds useful as olefin metathesis catalysts

Sulfur chelated ruthenium compounds represented by the following formula: ##STR00001##
wherein M indicates the ruthenium metal bound to a benzylidene carbon; R represents C.sub.1-C.sub.7 alkyl group or optionally substituted aryl; X.sub.1 and X.sub.2 each independently represent halogen; Y.sub.1 and Y.sub.2 each independently denote unsubstituted or alkyl-substituted phenyl; and Z independently represents hydrogen, electron withdrawing or electron donating substituent, with m being an integer from 1 to 4, and processes and compositions related thereto.