Transformed tetrahedron

L. D. S. Yadav, C. Awasthi, V. K. Rai, and A. Rai, A route to functionalized pyrimidines from carbohydrates via amine-driven dehydrative ring transformations, Tetrahedron Lett., 49 (2008) 2377-2380. 

Controlled racemisation of optically active organic compounds Prospects for asymmetric transformation. Tetrahedron, 53, 9417-9476. 

Anastas, P.T. (2010) Perspective on green chemistry the most challenging synthetic transformation. Tetrahedron, 66, 1026-1027. 

Kanomata N, Mishima G, Onozato J (2009) Synchronized stereocontrol of planar chirality by crystallization-induced asymmetric transformation. Tetrahedron Lett 50 4094-12... 

Ebbers, E. J. Ariaans, G. J. A. Houbiers, J. P. M. Bruggink, A. Zwanenburg. B. Controlled Racemization of Optically Active Compounds Prospects for Asymmetric Transformation, Tetrahedron 1997,53,9417-9476. 

Ebbers EJ, Ariaans GJA, Houbiers JPM, Bruggink A, Zwanen-burg B. Controlled racemization of optically active organic compounds prospects for asymemtric transformations. Tetrahedron 1997 53 9417-9476. 

Banks, M R, Cadogan, JIG, Gosney, I, Gaur, S, Hodgson, P K G, Highly regio- and stereospecific preparation of a new carbohydrate-based l,3-oxazin-2-one by the INIR method and its appUcation in some asymmetric transformations. Tetrahedron Asymmetry, 5, 2447-2458, 1994. 

Offer a mechanistic explanation for the following transformation Tetrahedron Lett., 2000, 41, 3411) HC... 

El-Wassimi MTM, Joigensen KA, Lawesson SO (1983) The reaction of t-butyl hypochlorite with thiocarbonyl compound - a convenient method for the C=S to C=0 transformation. Tetrahedron 39 1729-1734... 

The H4 system is the prototype for many four-elecbon reactions [34]. The basic tetrahedral sfructure of the conical intersection is preserved in all four-electron systems. It arises from the fact that the four electrons are contributed by four different atoms. Obviously, the tefrahedron is in general not a perfect one. This result was found computationally for many systems (see, e.g., [37]). Robb and co-workers [38] showed that the structure shown (a tetraradicaloid conical intersection) was found for many different photochemical transformations. Having the form of a tetrahedron, the conical intersection can exist in two enantiomeric structures. However, this feature is important only when chiral reactions are discussed. 

Kieslich, K. 1976, Microbial Transformations of Non-Steroid Cyclic Compounds, Thieme Stuttgart Kim, B. M. Sharpless, K. B. 1990, Tetrahedron Lett. 1990, 3003... 

C), and is much less reactive it is therefore safer and easier to handle, and is essentially non-toxic. The amorphous material can be transformed into various crystalline red modifications by suitable heat treatment, as summarized on the right hand side of Fig. 12.3. It seems likely that all are highly polymeric and contain three-dimensional networks formed by breaking one P-P bond in each P4 tetrahedron and then linking the remaining P4 units into chains or rings of P atoms each of which is pyramidal and 3 coordinate as shown schematically below ... 

The 12 even permutations of the 4 vertices correspond to the rotations which are deck transformations of the regular tetrahedron. 

Sletzinger, M., Lin, T., Reamer, R.A., Shinkai, 1. (1980) A Facile Transformation of BicycUc Keto Esters to Bisprotected ( )-8-Epithienamycin Via Enol Activation. Tetrahedron Letters, 21, 4221M224. 

Adam, W., Lazarus, M., Saha-Moller, C.R. and Schreier, P. (1998) Quantitative transformation of racemic 2-hydroxy acids into (R)-2-hydroxy acids by enantioselective oxidation with glycolate oxidase and subsequent reduction of 2-keto acids with D-lactate dehydrogenase. Tetrahedron Asymmetry, 9 (2), 351-355. 

Yokoyama, M., Kashiwagi, M., Iwasaki, M. et al. (2004) Realization of the synthesis of a,a-disubstituted carbamylacetates and cyanoacetates by either enzymatic or chemical functional group transformation, depending upon the substrate specificity of Rhodococcus amidase. Tetrahedron Asymmetry, 15, 2817-2820. 

These microporous crystalline materials possess a framework consisting of AIO4 and SiC>4 tetrahedra linked to each other by the oxygen atoms at the comer points of each tetrahedron. The tetrahedral connections lead to the formation of a three-dimensional structure having pores, channels, and cavities of uniform size and dimensions that are similar to those of small molecules. Depending on the arrangement of the tetrahedral connections, which is influenced by the method used for their preparation, several predictable structures may be obtained. The most commonly used zeolites for synthetic transformations include large-pore zeolites, such as zeolites X, Y, Beta, or mordenite, medium-pore zeolites, such as ZSM-5, and small-pore zeolites such as zeolite A (Table I). The latter, whose pore diameters are between 0.3... 

H. Kotsuki, T. Shimanouchi, R. Ohshima, and S. Fujiwara, Solvent-free organic reactions on silica gel supports. Facile transformation of epoxides to /i-halohy-drins with lithium halides, Tetrahedron, 54 (1998) 2709-2722. 

Alphand, V., Archelas, A. andFurstoss, R., Microbial transformations 16. One-step synthesis of a pivotal prostaglandin chiral synthon via a highly enantioselective microbiological Baeyer-Villiger-type reaction. Tetrahedron Lett., 1989, 30, 3663. 

Sonogashira K. Tohda, Y. Hagihara, N. Tetrahedron Lett. 1975, 4467. Richard Heck discovered the same transformation using palladium but without the use of copper J. Organomet. Chem. 1975, 93, 259. 

Zheng MY, Li L, Chen SF. (1983) Chemical transformations of qinghaosu, a peroxidic antimalarial. Tetrahedron 39 2941-2946. 

Note added in proof In the meantime we were able to realize the transformation in an olefin A. Reusing, K.-J. Echrier, Th. Kauffmann, Tetrahedron Lett, in press... 

Klok, J. Baas, M. Cox, H.C. de Leeuw, J.W. Schenck, P.A. (1984) Loliolide and dihydroactinidiolide in a recent marine sediment probably indicate a major transformation pathway of carot ioids. Tetrahedron Lett., 25, 5577-80. 

Yokoyama, A. Shizuri, Y. Misawa, N. (1998) Production of new carotenoids, astaxanthin glucosides, by Escherichia coli transformants carrying carotenoid biosynthaic genes. Tetrahedron Lett., 39,3709-12. 

Cheminat, A. and Brouillard, R., NMR investigation of 3-0(P-D-glucosyl)malvidin structural transformations in aqueous solutions. Tetrahedron Lett. 27, 4457, 1986. 

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