Direct Asymmetric α‐Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts

Publisher Summary This chapter discusses the use of pyrazole as antioxidants in motor fuels, medicine, and development of cine-film. Besides the traditional interest in pyrazole derivatives which have been the basis of numerous dyes and drugs, a number of pyrazole anesthetics have appeared. Recent studies have established that pyrazolines are intermediates in the synthesis of cyclopropanes; they act as effective chemical bleaching agents, and as a constituent of luminescent and fluorescent substances. Pyrazoles are stable compounds with relatively high boiling points. It is a colorless compound with a peculiarly penetrating sweetish smell. The introduction of substituents in the 3-, 4-, and 5-positions causes an increase in the boiling point, which is expected with increased molecular weight, but the boiling point falls sharply with substitution in the 1-position. Similarly, 1-substituted pyrazoles melt at temperatures significantly lower than the corresponding compounds with free N-H groups. Both of these anomalies are due to the particularly strong association of pyrazoles unsubstituted in position 1, as proved by cryoscopic determination, spectral studies, dipole moment measurement, and infrared spectroscopy.

Progress in Pyrazole Chemistry

2.3. Amides and Lactams 3435 2.4. Imides 3448 2.5. Thiophenes 3451 2.6. Thiazolines, Thiazoles, and Thiazines 3454 2.7. Dithiazoles 3456 2.8. Thiadiazoles 3456 2.9. Imidazolines and Pyrimidines 3456 2.10. Alcohols 3458 2.11. PdO to PdS 3461 2.12. Reduction 3462 2.13. Nucleotides, Purines, and Pyrimidines 3463 2.14. Miscellaneous 3467 2.15. P4S10 vs Lawesson’s Reagent (LR) 3473 3. Conclusion 3473 4. Acknowledgments 3473 5. References 3473

A Berzelius Reagent, Phosphorus Decasulfide (P4S10), in Organic Syntheses

Iminyl, amidyl, and carbamyl radicals from O-benzoyl oximes and O-benzoyl hydroxamic acid derivatives

This article surveys variants of the Claisen rearrangement that are of general use in stereoselective organic synthesis. Recent results concerning the influence of steric and electronic parameters on transition state geometries are highlighted. The impact of the Claisen methodology in modern synthetic strategy and its application for the preparation of highly functionalized derivatives is exemplified.

Kent C. Brannock

Papers

Preparation of Sunstituted 4-Pentenals

Hydroxymethylene Ketones. I. The Preparation of β-Ketodimethylacetals and Methoxymethylene Ketones

Preparation and Properties of 1,3-Dioxep-5-enes

Notes- Reactions of Ethyl Isobutenyl Ether

Hydroxymethylene Ketones. III. The Preparation of Methoxymethylene Ketones1