Triphenylphosphine-cobalt

Ti -Cyclopentadienyl(triphenylphosphine)cobalt reacts with phosphites and forms complexes of 1-alkoxyphosphole oxides 251 (R = Me, Et, Ph) through a step involving (ri -cyclopentadienyl)(phosphite)cobalt (80JA4363). (ri -Cp)Co(PF3)2 reacts with hexafluorobut-2-yne and 252 is formed, which hydrolyzes into 253 (X = OH) [73JCS(CC)583 75JCS(D)197]. The five-member ring has the envelope conformation, in which the carbon atoms are coplanar, and the phosphorus atom deviates from this plane in the direction opposite to the cobalt atom. The heterocycle is a four-electron donor relative to the metal center. 

The octacyclic dimer (+)-94 could be obtained in short order from the tetracyclic bromide (+)-93 via a Co(I)-mediated reductive dimerization protocol first implemented in our prior syntheses of (+)-chimonanthine (7), (+)-folicanthine (8), and (—)-calycanthine (9) [7]. Simple exposure of intermediate (+)-93 to tris (triphenylphosphine)cobalt(I) chloride [48] in acetone under anaerobic conditions rapidly afforded dimer (+)-94 in 46 % yield. While higher yields (52 % yield) could be obtained in tetrahydrofuran on small scale, performing the reaction in acetone reproducibly afforded higher yields on gram scales. Notably, the product was obtained in similar efficiency on multi-gram scale (43 % yield on 8-g scale)... 

A direct synthesis of the thiophene nucleus has been achieved by allowing air-stable cobaltacyclopentadiene complexes (66) to react with sulfur the organometallic complexes are prepared in variable yields in a stepwise fashion from f75-cyclopentadienyIbis(triphenylphosphine)cobalt (65) (Scheme 82) 147,148 Reactions of the complexes 66 with selenium and nitrosobenzene give rise to selenophenes and pyrroles, respectively. 

TRIMETHYLPENTANAL, 51, 4 TRIMETHYLSILYL AZIDE, 50, 107 Triphenylphosphine-cobalt(II) bromide, catalyst, 53, 30,... 

C. (n5-CYCLOPENTADIENYL)[l, l -(i 2-l,2-ETHYNEDIYL)DI-BENZENE](TRIPHENYLPHOSPHINE)COBALT AND (q5-CYCLOPENTADIENYL) (METHYL 3-PHENYL-q2-2-PROPYNOATE)(TRIPHENYLPHOSPHINE)COBALTt... 

E. [l,4-BIS(METHOXYCARBONYL)-2-METHYL-3-PHENYL-l,3-BUTADIENE-1,4-DIYL]-(ti5-CYCLOPENTADIENYL)-(TRIPHENYLPHOSPHINE) COBALT AND [1,3-BIS(METHOX YCARBONYL)-2-METH YL-4-PHENYL-1,3-BUT ADIENE-1,4-DI YL]-(q 5-C Y CLOPENT ADIENYL)-(TRIPHENYLPHOSPHINE)COBALTt... 

Dodecacarbonyltri-frarngw/o-osmium, 288 Iron carbonyl, 152 Lithium acetyl(carbonyl)nitrosyltris-(triphenylphosphine)cobaltate, 102 Molybdenum carbonyl, 194 Nickel carbonyl, 198 Pentacarbonyl(ethylmethoxymethylene)-chromium, 82... 

TRIH YDRIDO-TRIS (TRIPHENYLPHOSPHINE)-COBALT(HI) AND HYDRIDO (NITROGEN)-TRIS-(TRIPHEN YLPHOSPHINE) COBALT (I)... 

Trihydrido-tris(triphenylphosphine)cobalt(III) has been obtained thus far only by the following procedure.1 Since the compound is very sensitive to air, it must be prepared and handled in an atmosphere of hydrogen or argon by standard vacuum-line techniques. The vacuum filtration apparatus, shown in Fig. 3, is used in conjunction with the vacuum line. It is important that an excess of sodium tetrahydroborate be used otherwise some chloro-tris(triphenylphosphine)cobalt(I)2 will be obtained also. 

The crude trihydrido-tris(triphenylphosphine)cobalt(III) prepared above will pick up nitrogen directly to form the nitrogen complex. 

ChIorotris(triphenylphosphine)cobalt, CoCUPCQH,),], (1). This bright green, moderately air-stable complex is obtained by reaction of CoClitPlQHjljJj with P(C6Hs) and Zn in CHjCN. The reagent reacts with benzocyclobutenediones to insert the metal between the two carbonyl groups. 

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