Visible-light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross-coupling reactions, α-amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible-light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible-light-absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo- or metal catalysis.

Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

Alan Ford,† Hugues Miel, Aoife Ring,† Catherine N. Slattery,† Anita R. Maguire,*,†,‡ and M. Anthony McKervey* †Department of Chemistry and ‡School of Pharmacy, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland Almac Discovery Ltd., David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom Almac Sciences Ltd., Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, United Kingdom

Modern Organic Synthesis with α-Diazocarbonyl Compounds

Recent developments in the synthesis and utilization of chiral sulfoxides.

Hydrogen autotransfer in the N-alkylation of amines and related compounds using alcohols and amines as electrophiles.

10. Patented Literature 2616 10.1. Esterification 2616 10.2. Ether Formation 2619 10.2.1. Etherification without Cyclization 2619 10.2.2. Etherification with Cyclization 2624 10.3. N-Alkylation 2625 10.4. Other Reactions 2627 11. Summary and Outlook 2628 12. Note Added in Proof 2628 13. Abbreviations Used in This Review 2629 14. Acknowledgments 2629 15. Supporting Information Available 2630 16. References 2630

Mitsunobu and Related Reactions: Advances and Applications

N-Bromosuccinimide in Acetonitrile: A Mild and Regiospecific Nuclear Brominating Reagent for Methoxybenzenes and Naphthalenes

The results of reductions of some acyclic 2-keto sulfoxides (ArC(O)CH 2 S(O)R; Ar=Ph, 2-Py, 4-Py, and R=Me, p-Tol) and flexible and rigid 2-sulfinylcyclohexanone diastereomers with various metal hydrides are reported. The high stereoselectivity observed in i-Bu 2 AlH reactions can be explained by assuming its association with the sulfinyl oxygen and intramolecular hydride transfer via chair-like transition states. In the presence of ZnCl 2 the hydride transfer evidently takes place intermolecularly on the half-chair conformation adopted by the chelated species formed by 2-keto sulfoxides and ZnCl 2 . The reductions with LiAlH 4 involve lithium chelates to which hydride is intramolecularly transferred from associated AlH 4 − through the most stable transition state. In all cases, an important role of the stereoelectronic effects on the favored hydride approach is proposed

Stereoselective reductions of 2-keto sulfoxides with hydrides

A general and efficient biomimetic method for the synthesis of aldimines from aldehydes and compounds bearing the NH2 group in the presence of pyrrolidine as a catalyst has been developed. These organocatalytic reactions, based on the application of the concept of nucleophilic catalysis, proceed with outstanding yields in the absence of acids and metals under simple conditions and minimum experimental manipulation. The method has been mainly applied to the synthesis of N-sulfinyl and N-sulfonyl imines, but its general validity has been proven with the preparation of representative N-phosphinoyl, N-alkyl, and N-aryl imines. These unprecedented reactions, which presumably occur via iminium activation without requiring acidic conditions, are an interesting and competitive alternative to the classical methods for preparing aldimines.

José L. García Ruano

Papers

N-Bromosuccinimide in Acetonitrile: A Mild and Regiospecific Nuclear Brominating Reagent for Methoxybenzenes and Naphthalenes

Stereoselective reductions of 2-keto sulfoxides with hydrides

A general aminocatalytic method for the synthesis of aldimines.

Efficient synthesis of disulfides by air oxidation of thiols under sonication

A general method for the preparation of N-sulfonyl aldimines and ketimines.