A palladium complex generated in situ from [Pd(eta3-C3H5)(cod)]BF4 and DPPF is a good catalyst for benzylic alkylation of benzyl methyl carbonate with the carbanion of dimethyl malonates. The catalytic reaction is applicable to a wide range of the benzylations of benzylic esters with malonates. The catalytic activity was heavily affected by the bite angle of the bidentate phosphine ligand on palladium. DPEphos ligand is superior to DPPF in the case of palladium-catalyzed benzylic amination of benzylic esters.
Direct catalytic C-C bond-forming addition to N-unprotected ketimines is an efficient and straightforward method of synthesizing N-unprotected tetrasubstituted amines that eliminates prior protection/deprotection steps and allows facile transformation of the products. Despite its advantages, however, N-unprotected ketimines have difficulties in C-C bond-forming reactions, and only a limited number of reactions and substrates are reported compared with their N-protected counterparts. Herein we report that N-unprotected trifluoromethyl ketimines are effective for C-C bond-forming reactions using Mannich-type reactions as a model case. We demonstrate that Lewis acid catalysis was effective for promoting reactions with various N-unprotected trifluoromethyl ketimines, and thiourea organocatalysis was effective for promoting highly enantioselective reactions with various carbonyl nucleophiles, providing direct access to various N-unprotected α- and/or β-tetrasubstituted amino acid esters. Furthermore, direct construction of vicinal tetrasubstituted chiral carbon stereocenters was achieved for the first time in a highly enantio- and diastereoselective manner. These results demonstrate the potential of N-unprotected ketimines as substrates applicable to many other addition reactions.
[reaction: see text] The palladium complex prepared from DPPF and Cp(eta3-C3H5)Pd is an effective catalyst for the alkylation of active methine compounds with benzylic carbonates under neutral conditions. The addition of 1,5-cyclooctadiene brought about remarkable improvement in the lifetime of the palladium catalyst, which led to high yields of the desired benzylation products.
For a photobioreactor for mass-culturing microalgae, it is known that flashing light effect enhances the efficiency of photosynthesis. A dynamic model for photosynthesis was developed to elucidate this effect. A particular feature of the model is that discrete RuBP particles circulate in the Calvin cycle and their speeds in the cycle are determined by the amount of ATP generated in the photon reception process. This can realise the light saturation under continuous light and the flashing light effect under fluctuating illumination. Laboratory experiments were conducted to obtain model parameters by curve-fitting for Chaetoceros calcitrans. The present model demonstrates the light flashing effect moderately well and elucidates its mechanism reasonably.
Nomenclature
ADP= adenosine diphosphate A R = normalised ATP amount consumed as a discrete RuBP particle circulates in the Calvin cycle ATP= adenosine triphosphate f = (T L + T D ) −1 = frequency of light-dark cycle (s −1 ) FLE = flashing light effect GAP = glycerinaldehyde-3-phosphate I = irradiance (µE m −2 s −1 ) k a = proportional ratio of normalised ATP amount to I n c = frequency of circulation of a discrete RuBP particle in the Calvin cycle when there is sufficient ATP (s −1 ) n R = number of discrete RuBP particles that bond CO 2 in the unit time,1 s P = photosynthesis productivity per cell expressed by the oxygen accumulation (fmol h −1 ) P c = generated oxygen as a discrete RuBP particle circulates in the Calvin cycle (fmol) PGA = phosphoglycerate RuBP = D-ribulose-1,5-bisphosphate T D = duration of dark period (s) T L = duration of light periods (s) = T L (T L + T D ) −1 = ratio of light period to dark period [ATP] = instantaneous dimensionless amount of ATP [RuBP] = instantaneous number of discrete RuBP particles in the Calvin cycle 208
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