Andersen reaction

A -sulfinyl chiral auxiliaries have been used to prepare enantiopure tetrahydro-P-carbolines and tetrahydroisoquinolines in good yields under mild reaction conditions. Both enantiomers of V-p-toluenesulfinyltryptamine 46 could be readily prepared from the commercially available Andersen reagents.Compound 46 reacted with various aliphatic aldehydes in the presence of camphorsulfonic acid at -78 °C to give the A-sulfinyl tetrahydro-P-carbolines 47 in good yields. The major diastereomers were obtained after a single crystallization. Removal of the sulfinyl auxiliaries under mildly acidic conditions produced the tetrahydro-P-carbolines 48 as single enantiomers. 

The Andersen sulphoxide synthesis allows one also to synthesize a variety of a-heteroatom substituted sulphoxides starting from a-heteroatom stabilized carbanions and (—)-(S)-276. The selected examples shown in Scheme 3 are the best illustration of the generality of this approach. The reaction of enolates or enolate like species with (—)-(S)-276 has been used for the synthesis of optically active a-carbalkoxy sulphoxides. For example, treatment of (—)-(S)-276 with the halogenomagnesium enolates of -butyl acetate, t-butyl propionate or t-butyl butyrate resulted in the formation of ( + )-(R)-t-butyl p-toluenesulphinylcarboxylates 298367 (equation 163). 

Amino acids, sulphoxide, radiolysis of 909 a-Amino acids, reactions of 776, 777 a-Aminosulphones, synthesis of 176 Aminosulphonyl radicals 1093 Aminosulphoxides rearrangement of 740 synthesis of 336 Andersen synthesis 60 / -Anilinosulphoxides, synthesis of 334, 335 Anion radicals 1048-1050 ESR spectra of 1050-1054 formation of during electrolysis 963 during radiolysis 892-897, 899, 903 Annulation 778, 781, 801, 802 Antibiotics, synthesis of 310 Arenesulphenamides 740 Arenesulphenates 623 reactions of 282 rearrangement of 719 Arenesulphinates 824, 959 chiral 618... 

There has been some evidence of a higher antioxidant effect when both flavonoids and a-tocopherol are present in systems like LDL, low-density lipoproteins (Jia et al., 1998 Zhu et al, 1999). LDL will incorporate a-tocopherol, while flavonoids will be present on the outside in the aqueous surroundings. A similar distribution is to be expected for oil-in-water emulsion type foods. In the aqueous environment, the rate of the inhibition reaction for the flavonoid is low due to hydrogen bonding and the flavonoid will not behave as a chain-breaking antioxidant. Likewise, in beer, none of the polyphenols present in barley showed any protective effect on radical processes involved in beer staling, which is an oxidative process (Andersen et al, 2000). The polyphenols have, however, been found to act synergistically... 

And third, since virtually all enzymes [67], particularly those that catalyze phos-phoryl-transfer reactions [68 74], possess structures with at least two, discrete, relatively rigid structural domains, or lobes, separated by a deep cleft, the cytoplasmic portion of the H -ATPase polypeptide chain in the model of Fig. 2 is drawn in such a way as to suggest this situation. The proposed interdomain cleft is indicated by the arrow. No additional structural features of the ATPase molecule are implied in the model. In regard to comparisons with the Ca -ATPase, it is of interest to note that the two cytoplasmic domains proposed in Fig. 2 correspond to the Cl and C2 domains in the model of Andersen and Vilsen [53]. 

Kildahl-Andersen G, Bruas L, Lutnaes BF, and Liaaen-Jensen S. 2004. Nucleophilic reactions of charge delocalised carotenoid mono- and dications. Organic Biomolecular Chemistry 2(17) 2496-2506. 

Kildahl-Andersen G, Anthonsen T, and Liaaen-Jensen S. 2007. Studies on the mechanism of the Carr-Price blue color reaction. Organic Biomolecular Chemistry 5 3027-3033. 

Reaction of Grignard reagents with optically active sulfinate esters (150) is a particularly useful route to optically active sulfoxides and occurs with 100% inversion of configuration (Andersen et al., 1964). Substitution reactions of... 

The most important and widely used approach to chiral sulfoxides is the method developed by Andersen (5) based on the reaction between the diastereomerically pure (or strongly enriched in one dia-stereomer) menthyl arenesulfinates and Grignard reagents. The first stereospecific synthesis of optically active (+H7 )-ethyl p-tolyl sulfoxide 22 was accomplished in 1962 by Andersen (75) from (-)-(iS)-menthyl p-toluenesulfmate 45 and ethylmagnesium iodide. 

An alternative stereospecific synthesis of chiral sulfimides reported by Nudelman (137) consists of the reaction of the diastereomeric menthyl p-toluenesulfinimidoates 90 with Gri ard reagents giving the optically active sulfimide 91. This reaction, like the Andersen synthesis of chiral sulfoxides, proceeds with inversion of configura-... 

In addition to routes involving resolution and asymmetric synthesis, optically active sulfonium salts have been prepared in a stereospecific way by Andersen (158,159). Thus, synthesis of the optically active dialkyl-p-tolylsulfonium salts 114 from the optically active ethoxy-sulfonium salt 115 was accomplished by the addition of alkyl Grig-nard or dialkylcadmium reagents. This reaction occurs with inversion... 

The procedure most commonly used for the stereospecific preparation of optically active sulfoximides involves the reaction of optically active sulfoxides with arylsulfonyl azides in the presence of copper (98,118,131,178,179). This reaction occurs with retention of configuration at sulfur and with high stereospecificity. The stereospecific sulfoxide-sulfoximide conversion is a key reaction in the stereospecific sulfoxide-sulfimide-sulfoxiraide set of interconversions carried out by Cram and co-workers (98) and shown in Scheme 9. A similar cycle of interconversions studied independently by Andersen and co-workers (179) was used to determine the stereochemical course of the sulfoxide-sulfoximide transformation (see Scheme 10). 

The most frequently encountered reactions in organic sulfur chemistry are nucleophilic displacement reactions. The mechanism and steric course of reactions have been the main points of interest of research groups all over the world, in particular, Andersen, Cram, Johnson, and Mislow in the United States Kobayashi and Oae in Japan Kjaer in Denmark and Fava and Montanari in Italy. The results of these investigators have been discussed exhaustively in many reviews on sulfur stereochemistry. In a recent report on nucleophilic substitution at tricoordinate sulfur, the literature was covered by Tillett (10) to the end of 1975. Therefore only some representative examples of nucleophilic substitution reactions at chiral sulfur are discussed here. However, recent results obtained in the authors laboratory are included. 

In contrast to the widely investigated stereochemistry of nucleophilic substitution at optically active tricoordinate sulfur, there have been few similar studies with optically active tetracoordinate sulfur systems. Sabol and Andersen (174) were the first to show that the reaction of p-tolylmagnesium bromide with (-)-menthyl phenyl-methane[ 0- 0]sulfonate 140 proceeds with inversion of configuration. Thus, the Grignard reaction at the sulfinyl and sulfonyl centers takes place with the same stereochemistry. 

The amount of bromomethane broken down by this reaction in the body is not known, but increased levels of both methanol and bromide have been detected in exposed animals (Gargas and Andersen 1982 Honma et al. 1985). Bromomethane may also react with organic thiols (R-SH) to yield S-methyl derivatives ... 

Wendelbo, R., Akporiaye, D., Andersen, A., Dahl, I.M., and Mostad, H.B. (1996) Synthesis, characterization and catalytic testing of SAPO-18, MgAPO-18, and ZnAPO-18 in the MTO reaction. Appl. Catal. A, 142, L197-L207. 

Stability is also affected by pH, light, heat, and mechanical stress. Colors change depending on pH and on protonation and hydration reactions during storage. The most stable form, the flavylium cation, predominates at low pH (Torskangerpoll and Andersen, 2005). Stability is... 

T. Ruhland, K. Andersen and H. Pedersen, Selenium-linking strategy for traceless solid-phase synthesis Direct loading, aliphatic C-H bond formation upon cleavage and reaction monitoring by gradient MAS NMR spectroscopy, J. Org. Chem., 1998, 63, 9204-9211. 

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