Electron-rich benzofulvenes as effective dipolarophiles in copper(i)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides.

A series of benzofulvenes without any electron-withdrawing substituents were employed as 2π-type dipolarophiles for the first time to participate in Cu(i)-catalyzed asymmetric 1,3-dipolar cycloaddition (1,3-DC) reactions of azomethine ylides. An intrinsic non-benzenoid aromatic characteristic from benzofulvenes serves as a key driving force for activation of the electron-rich benzofulvenes. Utilizing the current methodology, a wide range of multi-substituted chiral spiro-pyrrolidine derivatives containing two contiguous all-carbon quaternary centers were formed in good yield with exclusive chemo-/regioselectivity and high to excellent stereoselectivity. Computational mechanistic studies elucidate the origin of the stereochemical outcome and the chemoselectivity, in which the thermostability of these cycloaddition products is the major factor.

Stereodivergent Construction of 1,4-Nonadjacent Stereocenters via Hydroalkylation of Racemic Allylic Alcohols Enabled by Copper/Ruthenium Relay Catalysis.

An unprecedented hydroalkylation of racemic allylic alcohols and racemic ketimine esters enabled by Cu/Ru relay catalysis has been developed via merging the ruthenium-catalyzed asymmetric borrowing-hydrogen reaction with a copper-catalyzed asymmetric Michael addition in a one-pot procedure. The current method enables the efficient preparation of highly functionalized δ-hydroxyesters bearing 1,4-nonadjacent stereocenters in good yields with high levels of diastereoselectivity and excellent enantioselectivity under mild reaction conditions. The full complement of the four stereoisomers of hydroalkylation products could be readily accessed by orthogonal permutations of two chiral metal catalysts. The current work highlights the power of relay catalysis for the stereodivergent construction of 1,4-nonadjacent stereocenters that were otherwise inaccessible.

Catalytic Asymmetric Benzylation of Azomethine Ylides Enabled by Synergistic Lewis Acid/Palladium Catalysis.

The synergistic chiral Lewis acid/achiral Pd catalyst system was successfully applied in the enantioselective benzylation of various imine esters, giving a range of α-benzyl-substituted α-amino acid derivatives in satisfactory yield with excellent enantioselectivity. It is worth noting that this strategy exhibits good tolerance for bicyclic and monocyclic benzylic electrophiles. Furthermore, the utility of this synthetic protocol was demonstrated by the expedient preparation of enantioenriched antihypertensive drug α-methyl-l-dopa.

[Chinese herbs application combined with operation for treating post-traumatic tibial osteomyelitis complicated with bone-skin defects].

OBJECTIVE: The aim of this study was to explore the method and clinical effects of integration of Chinese herbs and operation for the treatment of post-traumatic tibial osteomyelitis complication with bone-skin defect. METHODS: Among 28 patients with post-traumatic tibial osteomyelitis complicated with bone-skin defects, 18 patients were male and 10 females, ranging in age from 18 to 68 years, with an average of 32.5 years. All the patients were treated with transplantation of free iliac flaps to one-stage repair the bone-skin defects after infection controlled with Chinese herbs dressing. The curative effects were analyzed. RESULTS: All the patients were followed up and ranged from 8 to 56 months, with an average of 30 months. All of the flap survived, and the wounds got primary healing in 26 patients and secondary healing in 2 patients. All the grafted bone united in 2 to 14 months,with a mean time of 4.6 months. The osteomyelitis recurred in 2 patients and got healed by focal debridement. CONCLUSION: Chinese herbs application combined with operation for treating post-traumatic tibial osteomyelitis complicated with hone-skin defects is effective to control infection, one-stage repair the tissue defects, which is worthy popularizing.