Kishi model

However, a computational study124 shows that the Kishi model controls the stereoselectivity for (Z)-alkenes. Note also that in the Diels-Alder reactions of hexachloropentadiene with chiral alkenes, the inside alkoxy effect is attributed to electrostatic repulsion of the oxy group in the125 outside position with the chlorine atom of hexachloropentadiene in the 1-position. 

Scheme 8.20. (a) Kishi model for acyclic control in osmylation reactions [90]. (b) Double diastereoselectivity in an AD reaction [92],... 

K. Maekawa, R. Chaube and T. Kishi, Modeling of Concrete Performance Hydration, Microstructure Formation and Transport, E FN SPON, UK, London, 1999... 

Y. Komoda and T. Kishi, in J. M. Cassady andJ. D. Douros, eds.. Anticancer Agents Based on Natural Products Models, Academic Press, New York, 1980, Chapt. 10. 

The issue of stereochemistry, on the other hand, is more ambiguous. A priori, an aldol condensation between compounds 3 and 4 could proceed with little or no selectivity for a particular aldol dia-stereoisomer. For the desired C-7 epimer (compound 2) to be produced preferentially, the crucial aldol condensation between compounds 3 and 4 would have to exhibit Cram-Felkin-Anh selectivity22 23 (see 3 + 4 - 2, Scheme 9). In light of observations made during the course of Kishi s lasalocid A synthesis,12 there was good reason to believe that the preferred stereochemical course for the projected aldol reaction between intermediates 3 and 4 would be consistent with a Cram-Felkin-Anh model. Thus, on the basis of the lasalocid A precedent, it was anticipated that compound 2 would emerge as the major product from an aldol coupling of intermediates 3 and 4. 

The extremely high sensitivity of bacteriochlorins to various reactions makes their chemistry very difficult. This might also be one reason why methods for the total synthesis of bacteriochlorins had not, until very recently, been developed.13 Total synthesis of a tolyporphin model was reported by Kishi et al.13 using an approach that is very closely related to Eschenmoser s syntheses of hexahydroporphyrins from reduced linear tetrapyrroles by cyclization (see Section 1.5.1). 

Fig. 8.9 Possible mechanisms of the bioluminescence reaction of dinoflagellate luciferin, based on the results of the model study (Stojanovic and Kishi, 1994b Stojanovic, 1995). The luciferin might react with molecular oxygen to form the luciferin radical cation and superoxide radical anion (A), and the latter deproto-nates the radical cation at C.132 to form (B). The collapse of the radical pair might yield the excited state of the peroxide (C). Alternatively, luciferin might be directly oxygenated to give C, and C rearranges to give the excited state of the hydrate (D) by the CIEEL mechanism. Both C and D can be the light emitter.

The structures of PMs are trimeric, consisting of three molecules of PS and two molecules of methylamine that are condensed together (Table 9.5). In the structures of PMs, however, the bonds created by the condensation lack adjacent hydrogen atoms, making the connectivity assignment in 1H-NMR studies virtually impossible (see the 9-membered rings in Fig. 9.11). To circumvent this problem, a model compound of panal, K-l, having 13C-labeles at the C12 and C13 positions, has been synthesized at Kishi s laboratory (Harvard University) to make a model compound of PM (Stojanovic, 1995). 

Kawamiya, M., Kishi, M. J., Yamanaka, Y., and Suginohara, N. (1995). An ecological-physical coupled model applied to Station Papa. J. Oceanogr. 51, 635—664. 

Takagi Y, Takahashi J, Saiki H, Morizane A, Hayashi T, Kishi Y, Fukuda H, Okamoto Y, Koyanagi M, Ideguchi M, Hayashi H, Imazato T, Kawasaki H, Suemori H, Omachi S, lida H, Itoh N, Nakatsuji N, Sasai Y, Hashimoto N (2005) Dopaminergic neurons generated fiom monkey embryonic stem cells function in a Parkinson primate model. J Clin Invest 115 102—109. 

We selected the natural product thyrsiferol as an ideal target to test our ideas. Its total synthesis was envisioned to proceed as illustrated in the Scheme 28. The successful coupling between aldehyde 84 and vinyl iodide 82 via a Nozaki-Hiyama-Kishi (NHK) reaction [66] had been demonstrated previously [29]. We therefore sought to model our final steps after precedence presented by Forsyth for the union of these two fragments. The focus of our synthetic strategy centered around the stereoselective synthesis of the ABC framework (84) of thyrsiferol (1) as a scaffold to validate the scope of the Cp2TiCl reaction with epoxides toward the assembly of Q-C-glycosides and cyclic ethers. 

Topalov G, Kishi Y (2001) Chlorophyll Catabolism Leading to the Skeleton of Dinoflagellate and Krill Luciferins Hypothesis and Model Studies. Angew Chem Int Ed 40 4010... 

However, the stereochemistry of this osmylation would be opposite to Kishi s model which predicts an anti attack of the osmium tetroxide with respect to the 1-0R-function as shown by the conversion of 109 into 110. To circumvent this problem it was necessary to introduce the l-OR group first in the wrong configuration in order to... 

K Maekawa, T. Ishida and T. Kishi, Multi-scale Modeling of Concrete Performance Integrated Material and Structural Mechanics. Journal of Advanced Concrete Technology, Vol.l N 2 (2002) p.91... 

Morizane R, Lam AQ, Freedman BS, Kishi S, Valerius MT, Bonventre JV. 2015. Nephron organoids derived from human pluripotent stem cells model kidney development and injury. Nat Biotechnol 33(11) 1193-1200. 

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