Lactones combination table

Here and refer to the same solvents as listed in Table 1 f ethyl acetate. Appears not to be in ester combination with a necine (73). t Lactone acid, tt Dilactone. ... 

This also applies for protonations with optically active sulfonamides as the proton source (see table below)159. Whereas the highest selectivity (46% ee) is achieved with an (f ,f )-bissulfon-amide160, the lowest ee (5%) is obtained when the 4-methylphenylsulfonyl moiety is coupled to (S)-ethyl phenylalaninate. In the latter case, the highest ee (40%) is obtained when the (S)-alaninate is coupled with the (S)-camphorsulfonyl group. The stereogenicity of the cam-phorsulfonyl moiety is even more significant since its combination with the (/ )-alaninate still yields the (S)-lactone in 18% ee. 

Racemisation can be achieved with a variety of homogeneous catalysts. We selected the well-known Shvo catalyst (Scheme 2). Since many DKR processes have been successfully developed with the combination Novozym 435 and this Ru-based catalyst, the two catalysts are both compatible and complementary. In-situ racemisation of the terminal secondary alcohol of the propagating polymer chain should provide reactive chain ends, theoretically resulting in an enantiopure polymer in a 100% yield starting from the racemic monomer (Scheme 2). If the less reactive (RJ-6-MeCL is incorporated (which will occur since the selectivity for lactones is moderate with an E value of 12, see Table 2) a reactive R-chain end is obtained and propagation occurs instantly. In this way, both enantiomers of the monomer are consumed. 

The above table gives one of many applicable formulations, all of which contain lactone and polyoxyethylene glycol dialkyl ether solvents in combination with other components of the mixture. 

On the other hand, alkylzinc halides, in the absence of HMPA, display completely different results. For example, under similar conditions to those of run 1, Table 2, /3-zincioester does not provide the expected unsymmetrical ketone 8 in any detectable amounts instead, a mixture of two lactones and diethyl 4-oxopimeIate is produced in a good combined isolated yield (Scheme 26).The minor lactone may be derived by the allylation of the usual unsymmetrical ketone 8 at the keto function followed by lactoniza-tion, and the major lactone may be derived by the allylation of diethyl 4-oxopimelate. Indeed, under similar conditions, in the presence of benzaldehyde, benzaldehyde is selectively allylated to provide the homoaUyl alcohol in good yield, and diethyl 4-oxopimelate remains intact and is isolated in quantitative yield (Scheme 26). 

However, these methods suffer from low activities and/or narrow scope. Uemura and coworkers [74,7 5] reported an improved procedure involving the use of Pd(OAc) 2 (5 mol%) in combination with pyridine (20 mol%) and 3 A molecular sieves (500 mg per mmol of substrate) in toluene at 80 °C. This system smoothly catalyzed the aerobic oxidation of primary and secondary aliphatic alcohols to the corresponding aldehydes and ketones, respectively, in addition to benzylic and allylic alcohols. Representative examples are summarized in Table 5.7. The corresponding lactones were afforded by 1,4- and 1,5-diols. This approach could also be employed under fluorous biphasic conditions [76]. 

Parvistemonine (42) and didehydroparvistemonine (43) have an Q -methyl-)/-lactone ring positioned at C3. The structures of these alkaloids were established by a combination of spectroscopic methods (16,36,51), and by oxidation of parvistemonine (42) to didehydroparvistemonine (43) with Ag20 (16). The striking differences in almost all of the signals in the C-NMR data (Table XV) of parvistemoline (41) and parvistemonine (42) ranging from less than 1 ppm (Cll, CIS, and Cl6) to 11.1 ppm (CIO), compared to the chemical shift differences observed previously for alkaloids which differ only in the replacement of the carbonyl at C3 by the a-methyl-y-butyrolactone ring, makes the current structural assignment for these alkaloids doubtful. 

When G-ME and GAo-ME were evaluated concomitantly, G-ME induced a decreased leaf FW (Table 4), while GA3-ME induced an increased leaf FW and the combination of G-ME and GA3-ME was intermediate but not significantly different from the untreated material. -Diketone content (A/tg/g FW) was decreased by G-ME and GA3-ME, but where the compounds were applied concomitantly, there was not any significantly different from the untreated plants. Total wax (Amg/g FW) was Increased by G-ME, decreased by GA -ME, and the combination was not significantly different from the untreated plants. IL activity (/iM hydrazone product/mln/mg protein) was Increased by G-ME and GA3-ME. These data show 1) the lactone ring of GA was requisite for increased height and FW, 2) the rates of total epicuticular wax and jS-diketone accumulation was influenced by GA-type molecules without the lactone ring, and 3) IL activity was influenced by GA-type molecules without the lactone ring. 

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