33866-90-9Relevant articles and documents
Ketone Synthesis from Benzyldiboronates and Esters: Leveraging α-Boryl Carbanions for Carbon-Carbon Bond Formation
Lee, Boran,Chirik, Paul J.
supporting information, p. 2429 - 2437 (2020/03/03)
An alkoxide-promoted method for the synthesis of ketones from readily available esters and benzyldiboronates is described. The synthetic method is compatible with a host of sterically differentiated alkyl groups, alkenes, acidic protons α to carbonyl groups, tertiary amides, and aryl rings having common organic functional groups. With esters bearing α-stereocenters, high enantiomeric excess was maintained during ketone formation, establishing minimal competing racemization by deprotonation. Monitoring the reaction between benzyldiboronate and LiOtBu in THF at 23 °C allowed for the identification of products arising from deborylation to form an α-boryl carbanion, deprotonation, and alkoxide addition to form an "-ate" complex. Addition of 4-trifluoromethylbenzoate to this mixture established the α-boryl carbanion as the intermediate responsible for C-C bond formation and ultimately ketone synthesis. Elucidation of the role of this intermediate leveraged additional bond-forming chemistry and enabled the one-pot synthesis of ketones with α-halogen atoms and quaternary centers with four-different carbon substituents.
Copper-catalyzed direct benzylation or allylation of 1,3-azoles with N -tosylhydrazones
Zhao, Xia,Wu, Guojiao,Zhang, Yan,Wang, Jianbo
supporting information; experimental part, p. 3296 - 3299 (2011/04/24)
Cu-Catalyzed cross-coupling of N-tosylhydrazones with 1,3-azoles leads to the direct C-H benzylation or allylation. Cu carbene migratory insertion is proposed to play the key role in this transformation.
Chemistry of 1-Carbena-5-hexyne and Related Intermediates
Freeman, Peter K.,Danino Jose C.,Stevenson, Brian K.,Clapp, Gary E.
, p. 3867 - 3875 (2007/10/02)
Pyrolysis of the lithium salt of the tosylhydrazone of 4,4-dimethyl-6-heptyn-2-one (6b) as the dry salt over a temperature range of 150 to 200 deg C formed 4,4-dimethyl-1-hepten-6-yne (8), cis-4,4-dimethyl-5-hepten-1-yne (9), and trans-4,4-dimethyl-5-hepten-1-yne (10) with an average acyclic enyne composition of 11.1:4.9:84.0.The fourth product component, 1,5,5-trimethyl-1,3-cyclohexadiene (11a), was formed in 22-28percent relative to the acyclic enyne fraction.In order to test for a carbene to carbene equilibration, the lithium and sodium salts of 3,5,5-trimethyl-2-cyclohexenone tosylhydrazone were pyrolyzed.The lithium (sodium) salt formed 95.2percent (96.7percent) 11 and 4.8percent (3.3percent) 5,5-dimethyl-1-methylene-2-cyclohexene (19).Pyrolysis of the sodium salt of 4,4-dimethyl-6-heptyn-2-one (6c) generated an increased amount of cyclic product exhibiting a product composition of 72.0percent 11a, 8.7percent 8, 2.3percent 9, and 17.0percent 10, whereas the pyrolysis of 6c in the presence of 3.0 equiv of LiBr produced a product composition poorer in cyclic product (34.6percent 11a, 13.2percent 8, 5.2percent 9, and 47.2percent 10).Thermolysis of the lithium (sodium) salt of the tosylhydrazone of 2-heptanon-6-yne generates products with a reaction composition of 4.8percent (47.8percent) 1-methyl-1,3-cyclohexadiene (11b), 8.1percent (5.9percent) 1-hepten-6-yne (21), 29.9percent (11.4percent) cis-5-hepten-1-yne (22), and 57.3percent (35.1percent) trans-5-hepten-1-yne (23).In order to characterize the alkynylcarbenes formed in these decompositions, the related saturated systems were investigated by pyrolysis of the lithium and sodium salts of the tosylhydrazones of 2-heptanone and 4,4-dimethyl-2-heptanone.The mechanistic pathways for the decomposition of 2-diazo-4,4-dimethyl-1-heptyne are described in terms of (a) a pyrazole route and (b) a carbene to carbene rearrangement.
