75473-95-9

Upstream product

• 42843-52-7 (E)-3-bromo-3-hexene 
• 62673-31-8 benzyl(bromo)zinc 
• 16403-09-1 (3E)-3-iodo-3-hexene 
• 100-39-0 benzyl bromide 
• 75473-91-5 Bis-(1,2-dimethyl-propyl)-((Z)-1-ethyl-but-1-enyl)-borane 
• 175398-28-4 2,3-Diethylthiirane 1,1-dioxide 
• 108-48-5 2,6-dimethylpyridine 
• 928-49-4 hex-3-yne 
• 31406-67-4 tetra(benzyl)hafnium 

Relevant academic research and scientific papers

C(sp3)-H alkenylation catalyzed by cationic alkylhafnium complexes: Stereoselective synthesis of trisubstituted alkenes from 2,6-dimethylpyridines and internal alkynes

Dibenzylhafnium complexes 3a-d, supported by dianionic bidentate or tridentate ligands, upon activation via abstraction by either [Ph3C][B(C6F5)4] or B(C6F5)3 served as catalysts for the C(sp3)-H alkenylation of 2,6-dimethylpyridines with dialkylalkynes to give corresponding C(sp3)-H alkenylated products 6. Complex 3c, containing a pyridine arm in the ligand skeleton, exhibited the highest catalytic activity among 3a-d; initial addition of 2,6-dimethylpyridine (4a) to the C6D5Br solution of 3c followed by [Ph3C][B(C6F5)4] and 3-hexyne (5a) produced trisubstituted alkene 6aa in stereoselective manner in up to 50% yield without any byproducts, while the addition of 5a prior to 4a and [Ph3C][B(C6F5)4] to the C6D5Br solution of 3c generated 6aa, together with the formation of byproduct (E)-(2-ethylpent-2-en-1-yl)benzene (7). When an asymmetrical pyridine, 3-bromo-2,6-dimethylpyridine, was used as the coupling partner, the corresponding trisubstituted alkene was obtained selectively. Catalytically active cationic benzylhafnium complexes 8a-d, which were prepared by the reactions of 3a-d and B(C6F5)3, respectively, were characterized by 1H, 13C, and 19F NMR spectroscopy. Kinetic studies of the catalytic reaction between 4a and 4-octyne (5b) using 3c and [Ph3C][B(C6F5)4] in C6D5Br revealed that the catalytic reaction was zero-order for both 4a and 5b, indicating that the rate-determining step involved the C(sp3)-H bond activation of 4a by vinylhafnium intermediate 11c.

Oxidant-free direct coupling of internal alkynes and 2-alkylpyridine via double C-H activations by alkylhafnium complexes

We have developed a novel oxidant-free direct cross-coupling reaction of 2,6-lutidine and internal alkynes leading to five-membered carbocyclic compounds mediated by nonmetallocene cationic hafnium alkyl complexes. Mechanistic studies of the coupling reaction showed that the reaction begins with C(sp 3)-H bond activation via σ-bond metathesis, after which the coordinatively unsaturated hafnium center mediates further insertion, migration, and β-H elimination reactions to give five-membered carbocycles from readily available substrates.

Episulfone substitution and ring-opening reactions via α-sulfonyl carbanion intermediates

Three-membered cyclic sulfones undergo substitution on treatment with base-electrophile mixtures, such as LDA-Me3SiCl and Bu′-P4 phosphazene base-PhCHO, to give either substituted episulfones or the corresponding alkenes following loss of SO2. The structure of a trisilylated episulfone product, 2a, was determined by X-ray crystallography. In the absence of Me3SiCl, reaction of episulfones with lithium diisopropylamide results in ring-opening to give alkenyl sulfinate intermediates, which can be alkylated to give (E)-alkenyl sulfone products in stereoselective fashion.

HIGHLY SELECTIVE SYNTHESIS OF ALLYLATED ARENES AND DIARYLMETHANES VIA PALLADIUM-CATALYZED CROSS COUPLING INVOLVING BENZYLIC DERIVATIVES

The Pd-catalyzed cross coupling of either benzylzincs with alkenyl halides or alkenylalanes with benzyl halides provides highly selective and expeditious routes to allylated arenes.

THE PALLADIUM-CATALYSED CROSS-COUPLING REACTION OF 1-ALKENYLBORANES WITH ALLYLIC OR BENZYLIC BROMIDES. CONVENIENT SYNTHESIS OF 1,4-ALKADIENES AND ALLYLBENZENES FROM ALKYNES VIA HYDROBORATION

The reaction of allylic or benzylic bromides with 1-alkenyldisiamylboranes readily available from 1-alkynes in the presence of sodium hydroxyde and catalytic amounts of tetrakis-(triphenylphosphine)palladium to give corresponding 1,4-alkadienes or allylbe