Acetic route

This operates in the same way for Lil, Nal and [QASjl but there is further catalysis through the acetate route for Li. If the difference between exchange rates for Lil and Nal or [QASjl is attributed to the acetate route then the major part of the reaction may still be occurring through the HI route. 

Leonard, N.J., and Hauck, F.P., Jr. Unsaturated amines. X. The mercuric acetate route to substituted piperidines, -tetrahydropyridines... 

SCHEME 17.6 Chiral amino acid acetal route to the bicyclic intermediate. 

The total syntheses of the less common alkaloids cassamedine (35f) (427) and N-methylovigerine (25n) (458), and of some nornucipherine derivatives were also achieved (459). Thaliporphine (24g), domesticine (241), and glaucine (24h), can be synthesized via the p-quinol acetate route (415, 460, 461) (Scheme 11). 

Scheme 11. Synthesis of the aporphine alkaloids (24) via the p-quinol acetate route (413).

Similarly to the 2-oxo analogs, 2-thioxopenams have been obtained by several methods, according to the C2-C3 strategy, via the iV-malonate [172 174] and W-acetate routes [62, 175 177], and to the S-Cj strategy [135, 197, 198]. Additionally, ring contraction of 3-acetylthio-2-thiacephems [216] and 2-... 

Path A Mixed Acetal Route to Furans and Pyrroles 47... 

X = 0(24) NTs (25) Scheme 4 Mixed acetal route to furans and pyrroles. 

Confirmation that other anthraquinones may be formed by the acetate route in plant tissues has since been provided (Leistner, 1971 Fairbairn and Muhtadi, 1972). The results obtained from these experiments by degradation studies showed an alternate labeling pattern consistent with an acetate-ma-lonate origin (although malonate was not tested directly), as previously demonstrated in fungi (Gatenbeck, 1962 Shibata and Ikekawa, 1962). 

Because most IR bands characteristic of the various molybdate phases are masked by two broad absorption bands generated by silica at 472 and 802 cm, the interpretation of dte IR spectra in the range 1000-400 cm is not an easy task. The infrared investigations were therefore restricted to the silica samples loaded with 10 mol. % of active metals. Typical IR spectra of catalysts prepared by the acetate route are presented in fig. 2. Those of catalysts made from inorganic precursors were very poorly resolved. The main comments are as follows. 

The following comments can be formulated on the XRD results. It should be mentioned first that, if the interpretation of the powder X-ray diffiractograms is unambiguous in the case of the 10% loaded silica samples, it l omes harder for the samples loaded with 5 mol.% and sometimes really hazardous for those loaded with 2 mol.% only of active metals. In general, the quality of the diffraction patterns is significantly higher in the samples obtained by the acetate route than with the classical inorganic precursors. The silica support itself is amorphous. 

Under these conditions, no isomerization into the thermodynamically more stable a-isophorone was observed. Remarkably, when the latter was subjected to the same reaction conditions, only hydrogenation took place, showing the general reactivity problems of enone hydroformylation [152]. Since the application of lower syngas pressure (100-150 bar) in the hydroformylation of P-isophorone also mainly yielded the hydrogenation product, the carbonyl group was protected as acetal (Route II) [152]. Surprisingly, under hydroformylation conditions (90 bar, 100 C), the exocyclic aldehyde was formed as the major product, obviously due to a prior Rh-mediated isomerization process. 

Scheme 2.75 The leaction of iV-aryl-2-nitrosoanilines with sulfones (route a), acetates (route b) and phosphonoacetates (route b)...

Fig. 18. Biogenesis of mono- and of di-anthraquinones by the poly-acetate route. Acetate-poly mate precursors provide same labelling pattern given in upper half... 

Acyl-enzyme complexes are crucial intermediates in all lipase catalyzed reactions and thus the lipases first form an acyl-enzyme complex with the acyl donor. Eq. (8.75) displays a sequential two-step mechanism for enzymatic kinetic resolution of J4-l-phenyl ethyl alcohol to i4-l-phenyl ethyl acetate (route N ). 

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