33866-90-9Relevant academic research and scientific papers
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.
Formal carbon insertion of n-tosylhydrazone into B-B and B-Si bonds: Gem-diborylation and gem-silylborylation of sp3 carbon
Li, Huan,Shangguan, Xianghang,Zhang, Zhikun,Huang, Shan,Zhang, Yan,Wang, Jianbo
supporting information, p. 448 - 451 (2014/04/03)
A convenient method is developed to synthesize 1,1-diboronates from the corresponding N-tosylhydrazones. This method is also applicable to synthesize 1-silyl-1-boron compounds. Meanwhile, derivatization and consecutive Pd-catalyzed cross-coupling reaction
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.
Synthetic studies toward the kempane diterpenes. Diels-Alder additions to bicyclic dienes
Liu, Chunjian,Bao, Guanglin,Burnell, D. Jean
, p. 2644 - 2656 (2007/10/03)
Diels-Alder additions of 2,6-dimethyl-p-benzoquinone to the bicyclic dienes 24, 30 and 32 took place with very high regio-, stereo- and facial selectivity. Reduction and then alkylation of a tetracyclic adduct with 1,3-dithienium tetrafluoroborate provided compound 56, which has the correct stereochemistry at three key carbons for elaboration to the kempane diterpenes. Exploratory reactions with tricyclic model compounds and with tetracyclic adducts have been used to assess the development of the desired stereochemistry about the decalin moiety. X-Ray structures for 52, 53 and 59 were determined.
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.
