5664-17-5Relevant articles and documents
THE IR, RAMAN AND NMR SPECTRA AND CONFORMATIONS OF CYCLOHEXYLALLENE
Gatial, A.,Horn, A.,Klaeboe, P.,Nielsen, C. J.,Pedersen, B.,et al.
, p. 59 - 66 (1990)
Three conformers of cyclohexylallene, designated I, II and III, were observed in the IR and Raman spectra.Metastable crystals formed by annealing an amorphous solid from 80 K to 140 K, and crystals formed under a pressure of 30 kbar at ambient temperature, contained conformer II.The stable crystals obtained after heating the metastable crystals to 195 K contained conformer I.The conformer III was observed as a minor component in a nitrogen matrix heated to 900 K before deposition.Negligible intensity variations between the bands of conformer I and II were observedwith nozzle temperatures 300-900 K in the argon and nitrogen matrices, indicating a ΔH0(I-II) below 0.4 kJ mol-1 while ΔH0(III-II) was equal to 6.5 kJ mol-1 and a barrier higher than ca. 11 kJ mol-1 was observed between the latter.Variable temperature measurements in Raman indicate ΔH0(I-II) ca. 0.9 kJ mol-1 in the liquid.The 13C NMR spectra show that in deuteromethanol solution the equatorial conformer dominates ( = 2percent a at 193 K, ΔG0(a-e) ca. 6.4 kJ mol-1).Analysing the temperature dependence of the vicinal H-H coupling across the cyclohexane - allene carbon bond on the basis of a gauche anti equilibrium it is found 40percent anti and 60percent gauche in methanol solution at ambient temperature.We conclude that the abundant conformers II and I being respectively the anti and the gauche conformer, while III is the anti axial conformer.
Preparation of (E)-1,3-Enyne Derivatives through Palladium Catalyzed Hydroalkynylation of Allenes
Liu, Zhi-Kai,Yang, Ying,Zhan, Zhuang-Ping
supporting information, p. 1589 - 1597 (2022/01/20)
A general and efficient palladium catalyzed hydroalkynylation of allenes was developed to produce synthetically versatile (E)-1,3-enyne derivatives with high regio- and stereoselectivity. This catalytic system proceeded under mild conditions and was compatible with a broad range of substrates, especially for allenes without electron-bias groups. This work further broadens the synthetic potential of these scaffolds in organic synthesis and medicinal chemistry.
Copper(ii)-catalyzed protoboration of allenes in aqueous media and open air
Nekvinda, Jan,Santos, Webster L.,Snead, Russell F.
supporting information, p. 14925 - 14931 (2021/09/04)
A method has been developed for the facile Cu(ii)-catalyzed protoboration of monosubstituted allenes in aqueous media under atmospheric conditions. The reaction occurs site selectively, favoring internal alkene protoboration to afford 1,1-disubstituted vinylboronic acid derivatives (up to 93?:?7) with modest to good yields. The method has been applied to a variety of phenylallene derivatives as well as alkyl-substituted allenes. This journal is
Enantioselective Copper-Catalyzed Three-Component Carboboronation of Allenes: Access to Functionalized Dibenzo [b,f][1,4]oxazepine Derivatives
Deng, Hao,Meng, Ziwei,Wang, Sifan,Zhang, Zheming,Zhang, Yaqi,Shangguan, Yu,Yang, Fazhou,Yuan, Dekai,Guo, Hongchao,Zhang, Cheng
supporting information, p. 3582 - 3587 (2019/07/17)
A copper-catalyzed enantioselective three-component difunctionalization of allenes with seven-membered cyclic imines and bis(pinacolato)diboron (B2(Pin)2) to approach functionalized dibenzo[b,f][1,4]oxazepine derivatives is developed. The chiral products are obtained in up to 81% yield, >20:1 dr, and 98% ee when either a chiral diphosphine ligand or a chiral ferrocenyl-based P,N-ligand is used. Furthermore, the reaction exhibits reversed diastereoselectivities when the chiral diphosphine ligand and the chiral P,N-ligand are used respectively. (Figure presented.).
