A set of acyclic all‐carbon α‐aryl quaternary aldehydes was synthesized by intermolecular palladium‐catalyzed asymmetric allylic alkylation (Pd‐AAA). Hydroxyacrylates were used as unprecedented nucleophilic counterparts instead of widely used ketone substrates. This produced a very rare all‐carbon quaternary aldehyde. Chiral ligand (R,R)‐L3 was found to be optimal in this Pd‐AAA reaction and provided good to excellent yields (75–99 %) and enantioselectivities (75–94 %) with a range of analogs.
A stereoselective synthesis of carbonates derived from 3-hydroxy-2-aryl acrylates was devised that can form the Zor E-stereoisomer in very high Z/E ratios (50:1 and 1:99, respectively). The stereochemical outcome depends on the choice of base, addition of TMEDA and reaction temperature. The Zand E-stereoisomers have different reactivities towards the DAAA reaction, with the E-stereoisomer displaying both greater reactivity and enantiodifferentiation with chiral ligands. The DAAA of E-stereoisomer analogues takes place in excellent yields ranging from 96-99% and enantioselectivities ranging from 42-78% ee.
Iron‐alkyl complexes are found as intermediates in a variety of homogenous organometallic reactions. The chapter deals with the synthesis, stability and reactions of iron‐alkyl complexes. Wilkinson and Piper in 1956 were the first to report an iron‐alkyl complex, and these investigations lead to the discovery of a whole range of reactions involving these complexes. This chapter will firstly cover the preparation of iron‐alkyl complexes, followed by the main categories of reactions in which these complexes take part, mainly CO insertion reactions and electrophilic cleavage reactions. A brief account of the role of FpMe (Fp = CpFe(CO)
2
) complexes in catalytic processes are also included in this chapter.
First Example of the Intermolecular Palladium-Catalyzed Asymmetric Allylic Alkylation of Hydroxyacrylates: Synthesis of All-Carbon -Aryl Quaternary Aldehydes. -A novel intermolecular asymmetric Pd-catalyzed alkylation of 3-hydroxy-2-arylacrylates is developed using a C 2-symmetric diphenylphosphine derivative as catalytic ligand. The process allows the synthesis of -allylated 2-aryl all-carbon quaternary aldehydes in high yields and high enantioselectivities. -(ASAD, S. A.; ULICKI, J.; SHEVYREV, M.; UDDIN, N.; ALBERCH, E.; HOSSAIN*, M. M.; Eur. J. Org. Chem. 2014, 26, 5695-5699, http://dx.
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