A silylene-stabilized ditin(0) complex and its conversion to methylditin cation and distannavinylidene.

Due to their intrinsic high reactivity, isolation of tin(0) complexes remains challenging. Herein, we report the synthesis of a silylene-stabilized ditin(0) complex (2) by reduction of a silylene-supported dibromostannylene (1) with 1 equivalent of magnesium (I) dimer in toluene. The structure of 2 was established by single crystal X-ray diffraction analysis.

Synthesis and Reactivity of N-Heterocyclic Silylene Stabilized Disilicon(0) Complexes.

Synthesis and reactivity of disilicon(0) complexes are of fundamental and application importance. Herein, we report the development of an N-heterocyclic imino-substituted silylene (1), which has strong σ-donating ability and is significantly sterically hindered. The one-pot reaction of this silylene with [IPr→SiCl ] (IPr=1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene) and KC (2 equiv) in THF at -30 °C leads to a silylene-ligated disilicon(0) complex (2), isolated as red crystals in 60 % yield.

Deoxygenation of Nitrous Oxide and Nitro Compounds Using Bis(N-Heterocyclic Silylene)Amido Iron Complexes as Catalysts.

Herein, we report the efficient degradation of N O with a well-defined bis(silylene)amido iron complex as catalyst. The deoxygenation of N O using the iron silanone complex 4 as a catalyst and pinacolborane (HBpin) as a sacrificial reagent proceeds smoothly at 50 °C to form N , H , and (pinB) O. Mechanistic studies suggest that the iron-silicon cooperativity is the key to this catalytic transformation, which involves N O activation, H atom transfer, H release and oxygenation of the boron sites.

A unified approach for divergent synthesis of contiguous stereodiads employing a small boronyl group.

Acyclic contiguous stereocenters are frequently seen in biologically active natural and synthetic molecules. Although various synthetic methods have been reported, predictable and unified approaches to all possible stereoisomers are rare, particularly for those containing non-reactive hydrocarbon substituents. Herein, a β-boronyl group is employed as a readily accessible handle for predictable α-functionalization of enolates with either syn or anti selectivity depending on reaction conditions.

Secondary amines as coupling partners in direct catalytic asymmetric reductive amination.

The secondary amine participating asymmetric reductive amination remains an unsolved problem in organic synthesis. Here we show for the first time that secondary amines are capable of effectively serving as N-sources in direct asymmetric reductive amination to afford corresponding tertiary chiral amines with the help of a selected additive set under mild conditions (0-25 °C). The applied chiral phosphoramidite ligands are readily prepared from BINOL and easily modified.

Direct Asymmetric Reductive Amination for the Synthesis of ()-Rivastigmine.

In this article we demonstrate how asymmetric total synthesis of ()-rivastigmine has been achieved using direct asymmetric reductive amination as the key transformation in four steps. The route started with readily available and cheap -hydroxyacetophenone, through esterification, asymmetric reductive amination, -diphenylmethyl deprotection and reductive amination, to provide the final ()-rivastigmine in 82% overall yield and 96% enantioselectivity. In the asymmetric reductive amination, catalysed by the iridium⁻phosphoramidite ligand complex and helped by some additives, the readily prepared 3-acetylphenyl ethyl(methyl)carbamate directly reductively coupled with diphenylmethanamine to yield the chiral amine product in 96% and 93% yield.