2.2. Thioether Oxidation 2139 2.3. Miscellaneous Oxidations 2144 3. Enantioselective Reduction Processes 2145 4. Enantioselective Nucleophilic Addition Processes 2147 4.1. Alkylation Reactions 2147 4.1.1. Aldehydes as Electrophiles 2148 4.1.2. Ketones as Electrophiles 2161 4.2. Allylation Reactions 2163 4.2.1. Aldehydes as Electrophiles 2163 4.2.2. Ketones as Electrophiles 2171 4.3. Arylation/Alkenylation Reactions 2171 4.4. Alkynylation Reactions 2172 4.4.1. Aldehydes as Electrophiles 2172 4.4.2. Ketones as Electrophiles 2174 4.5. Cyanation Processes 2174 4.5.1. Aldehydes as Electrophiles 2174 4.5.2. Ketones as Electrophiles 2179 4.6. Aldol-Type Reactions 2181 4.7. Pinacol Coupling Processes 2183 4.8. Miscellaneous Additions 2184 5. Enantioselective Friedel−Crafts Processes 2185 6. Enantioselective Cycloaddition Processes 2186 6.1. Diels−Alder Reactions 2186 6.2. [3+2]-Cycloaddition Reactions 2190 6.3. Pauson−Khand Reactions 2190 6.4. Cyclopropanation Process 2190 7. Kinetic Resolution Processes 2191 8. Enantioselective Desymmetrization Reactions 2195 9. Miscellaneous Reactions 2197 10. Conclusions and Outlook 2199 11. Acknowledgments 2199 12. References 2199

In the arena of enantioselective synthesis, titanium complexes wear the laurel wreath.

Data on the use of sulfones and sulfoxides in total stereo-, regio- and enantioselective syntheses of natural compounds published over the last 15–20 years are discussed and classified into the most important types of reactions. The bibliography includes 420 references.

http://iopscience.iop.org/article/10.1070/RC1996v065n02ABEH000204/pdf

Sulfones and sulfoxides in the total synthesis of biologically active natural compounds

We report here a new approach to the discovery of fluorescent chemosensors in which a new signaling mechanism allows a core fluorophore to be used in a combinatorial search for new binding events, thus reversing the reigning discovery paradigm.

Reversing the discovery paradigm: a new approach to the combinatorial discovery of fluorescent chemosensors.

Z-selective Horner-Wadsworth-Emmons reaction of ethyl (diarylphosphono)acetates using sodium iodide and DBU

Total synthesis of donaxaridine

A one-pot procedure for the reductive alkylation of US -keto sulfones is described. The method proceeds by a lithium in liquid ammonia desulfurization of the starting US -keto sulfone, resulting in regiospecific generation of an intermediate enolate. Subsequent admixture of tributyltin chloride followed by addition of the alkylating agent in HMPA generates the C( )-alkylated product in good yield and with excellent regiocontrol. Thus, 2-(phenylsulfonyl)-5-(2-propenyl)cyclopentanone gives 2,5-di(2-propenyl)cyclopentanone in 71% isolated yield with <1% of 2,2-di(2-propenyl)cyclopentanone detected in the crude reaction mixture. Experiments are presented which underscore the advantages of this procedure over traditional -alkylation/desulfurization protocols. 20 references, 1 table.

Desulfurization/α-alkylation of β-keto sulfones

Intramolecular Diels-Alder reaction of 1-nitrodeca-1,6,8-trienes

Synthese d'une decahydro indacenone par reaction intramoleculaire de Diels Alder a partir de l'acide ethyl-2 methyl-3 pentene-4 oique. Structure cristalline d'une lactone intermediaire

Ikarugamycin: total synthesis of the decahydro-as-indacene portion

OBJECTIVES To develop a standard technique for evaluation of racehorse shoes, to assess homotypic variation (interlimb variation) in shoe characteristics, and to determine whether shoe characteristics varied with age and sex. DESIGN Cross-sectional study. ANIMALS Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994. PROCEDURE Shoe characteristics were measured on horses examined after death. Percentage of agreement was used to compare shoe characteristics between limbs (homotypic variation). Using chi 2 analysis, shoe characteristics were compared between horses grouped by age and sex. RESULTS Toe grabs were present on 90.5% of horses, and rim shoes were present on 15.9% of horses. Heel traction devices were less frequent on front (2.5%) than rear (6%) hooves. Pads were present on 24.9% of horses, with bonded rim pads most common. Special types of shoes were present cn 5% of horses. Percentage of agreement between left and right front hooves and between left and right rear hooves was high (20/25 variables; % agreement > or = 99). In contrast, percentage of agreement between left front and left rear hooves and between right front and right rear hooves was low (2/25 variables; % agreement > or = 99). Presence of a pad was significantly (P < 0.05) associated with age, and several shoe variable (size, presence of a special shoe, overall wear matched) were significantly (P < 0.05) associated with sex. CLINICAL RELEVANCE Except for variables related to special shoes, wear, and weight, 1 shoe for the respective fore- or hind limbs could be used as an indicator for the contralateral shoe worn by Thoroughbred racehorses without substantial loss of information. However, 1 shoe could not be used as an indicator for shoe characteristics of all 4 limbs. Some shoe characteristics are associated with age and sex, and these variables should be considered possible confounders in studies of shoe characteristics.

Michael J. O'Brien

Papers

Desulfurization/α-alkylation of β-keto sulfones

Intramolecular Diels-Alder reaction of 1-nitrodeca-1,6,8-trienes

Ikarugamycin: total synthesis of the decahydro-as-indacene portion

Postmortem evaluation of homotypic variation in shoe characteristics of 201 Thoroughbred racehorses

Desulfurization/α-Alkylation of β-Keto Sulfones.