Syntheses of the type AC

With the bidentate o-(diphenylphosphino)benzaldehyde (PO) and o-[(diphenylphosphino)benzylidene]aniline (PN) ligands the complexes [ReX(CO)3(PO)] (X is halide, 94) and [ReX(CO)3(PN)] (X is halide, 95) have been synthesized and characterized, starting from [ReX(CO)5] (X is Br, Cl) [92]. Using the same starting material, complexes of the type/ac-[Re(CO)3(K 3-L) (96) were also prepared, where L is a phosphorus-containing heterotridentate ligand, obtained by condensation of 2-(diphenylphosphino)aniline with several salicylaldehyde derivatives (Scheme 24) [93]. 

Syntheses from AB and AC Fragments. A considerable number of investigations has been devoted to the perfection and subsequent development of syntheses of the type AB - C described in Schemes 35-39. We must first mention work on the improvement of methods of obtaining the main starting materials, 2-aligrl-l,3-cyclo-pentanediones, both by the intramolecular acylation of y-keto acids [1073, 1074] and by the reaction of succinic anhydride with ketone enol acetates [1075] and with alkylacetic acids [1076] in the presence of AICI3. 

Azabuta-l, 3-dienes of the type (CF3)aC N CH CRiR> (R = Me, Pr , or Ph R = Me or H) have been synthesized via allylic bromination (iV-bromosuccinimide) of imines obtainable by base-induced decomposition of 2,2-bis(trifluoromethyl)-5-oxazolidinones [from (CFj)gCO -t-a-amino acids ], followed by dehydrobromination (tertiary amines) of the monobromides (CF,)2CH-N CH CBrR R so obtained. The azadienes undergo 1,4-additions with bromine, with primary or secondary amines [R H R = PhCHj-NH, moipholino, or piperidino), and with thiols... 

Ley and Schanze [14, 68] have synthesized a series of PPE-type polymers that contain/ac-(5,5 -diethynyl-2,2 -bipyridine)Re(I)(CO)3Cl as part of the n-conju-gated main chain by a Pd-mediated coupling reaction, as illustrated in Scheme 9. The polymers differ with respect to the mole ratio of 4,4 -diethynylbiphenyl (59) and (5,5 -diethynyl-2,2 -bipyridine)Re(l)(00)301 (58) used in the polymerization reaction mixture. Four different polymers have been prepared and contain 0 (Po), 10 (Pio), 25 (P25), and 50 (P50) mol% of the Re(I) repeat units in the polymer chain, respectively (Scheme 9). 

An especially efficient reagent of this type is the boron-containing five-membered ring compound shown in Figure 3.30. Since this reagent is quite difficult to synthesize, it has not been used much in asymmetric synthesis. Nonetheless, this reagent will be presented here simply because it is particularly easy to see with which face of aC=C double bond it will react. 

Summary Novel potential o ligands of the l,4 -silaspiro[tetralin-l,4 -piperidine] type (compounds lb - 4b, isolated as hydrochlorides) and rac-sila-venlafiixine (rac-5b, a silicon analog of the serotonin/noradrenaline leuptake inhibitor roc-venla xine (rac-5a)) were synthesized. In addition, the sila-venlafaxine enantiomers (i )-5b and (S)-5b and the sila-venla xine derivatives / ac-6-HCl and rac-T-HCl were prepared. Compounds 3b-HCl and rac-Sb-HCl were structurally characterized by single-crystal X-ray diffraction, and rac-Sa, rac-Sh, rac-6, and rac-7 were pharmacologically characterized. 

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