Synthesis最新文献

Ionic liquids, nonvolatile salts featuring a melting point below 100 °C, are one of the few alternative solvents for environmentally friendly processes. However, like most molecular solvents, they are usually prepared by means of building blocks derived from fossil oil. Fortunately, an increasing number of ionic liquids are synthesized starting from renewable natural products such as sugars and amino acids. In the present review, we describe the detailed synthesis and applications of the biosourced ionic liquids reported in the literature over the last four years.

1 Introduction

2 Carbohydrate-Based Ionic Liquids

3 Amino Acid Based Ionic Liquids

4 Terpene-Based Ionic Liquids

5 Miscellaneous Ionic Liquids

6 Conclusion

Reductive functionalization of C–C unsaturated systems, including alkenes and alkynes, with a range of hydroelements (H[E]) is one of the most fundamental and highly practical methods for the synthesis of functionalized hydrocarbons. Since the resultant hydrocarbon products have strong applicability as synthetic intermediates, numerous homogeneous organo(metallic) catalysts have been intensively utilized to date for reductive functionalization reactions. In particular, well-defined transition-metal-based catalysts capable of controlling the regio- or stereoselectivity of a product by harnessing the addition of H[E] (E = H, B, Si, Ge) into C_α–C_β unsaturated bonds have drawn special attention. In this review, we describe recent examples of transition-metal catalytic systems (M = Fe, Co, Rh, Pd, Ni) for regio- or stereodivergent hydroelementation reactions of (conjugated) alkenes, alkynes, and allenes to give a pair of isomeric products in high selectivities from the same starting compounds simply by variation of the ligand. Mechanistic aspects of the ligand-controlled selectivity divergence are discussed in detail on the basis of experimental observations and/or computational insights.

1 Introduction

2 Hydroelementation of Alkenes and Alkynes

3 Hydroelementation of Conjugated Dienes and Diynes

4 Hydroelementation of Allenes

5 Summary and Outlook

In this Short Review, we discuss radical reactions using 1,2-bis(phenylsulfonyl)ethylene (BPSE), which has drawn significant attention as a versatile building block for (phenylsulfonyl)ethenylation. Regardless of its E or Z form, BPSE exhibits reliable reactivity towards the attack of alkyl and aryl radicals in order to function as a reliable radical C2 synthon.

1 Introduction

2 Use in Radical Chain Reactions

3 Use in Reactions Utilizing an Electron-Transfer Process

4 Use in Radical-Based C–H Alkenylation

5 Conclusion

A new and facile route for the one-pot synthesis of 3,12-dicyano-3,6,9,12-tetraazadispiro[5.2.5⁹.2⁶]hexadecane-6,9-diium dibromide as a dispirotripiperazine source was introduced by the simple reaction of 1,4-diazabicyclo[2.2.2]octane (DABCO) with cyanogen bromide (BrCN) under mild condition at room temperature. The hydrolysis of dicyanamide moieties in the prepared dispiro compound gave 3,12-diaza-6,9-diazoniadispiro[5.2.5.2]hexadecane dibromide with the dispirotripiperazine (6-6-6) core. The molecular structure of the new compound was characterized by FT-IR, ¹H, ¹³C, HSQC NMR spectroscopy, mass and CHN analysis, and X-ray crystallography technique.

Reported here is the iridium-catalyzed regio- and enantio­selective secondary benzylic C–H borylation using benzothiazole as the directing group. Various monosubstituted 2-arylalkylbenzo[d]thiazole were well-tolerated, affording the corresponding products in moderate to good yields with good enantioselectivity. The C–B bond in one boryl­ated product could undergo stereospecific transformations to form a series of C–C and C–heteroatom bonds.

A straightforward and efficient electrochemical method for the anodic oxidative selenenylation of 2-(2-arylallyl)phenols and a 2-(3-arylbut-3-en-1-yl)phenol with diselenides under ambient air conditions has been outlined. This method allows for the synthesis of selenyl-dihydrobenzofurans and a chromane featuring a sterically hindered tetrasubstituted carbon center, demonstrated through 25 examples with yields reaching up to 98%. Initial mechanistic investigations suggest the likely participation of pivotal seleniranium cation species in regulating the reactivity.