Formation of Three New Bonds and Two Stereocenters in Acyclic Systems by Zinc-Mediated Enantioselective Alkynylation of Acylsilanes, Brook Rearrangement, and Ene-Allene Carbocyclization Reactions
Citations Over TimeTop 13% of 2014 papers
Abstract
Diastereoisomerically pure (dr > 99:1) and enantiomerically enriched (er up to 98:2) substituted propargyl diols possessing a tertiary hydroxyl group were synthesized in a single-pot operation from simple acylsilanes through a combined catalytic enantioselective alkynylation of acylsilanes, followed by an allenyl-Zn-Brook rearrangement and Zn-ene-allene (or Zn-yne-allene) cyclization reaction. Two remarkable features of these reactions are the near complete transfer of chirality in the allenyl-Zn-Brook rearrangement and the highly organized six-membered transition state of the Zn-ene-allene carbocyclization found by DFT calculations. In this process, three new bonds and two new stereogenic centers are created in a single-pot operation in excellent diastereo- and enantiomeric ratios. DFT calculations show that the allenyl-Zn-Brook rearrangement occurs in preference to the classic [1,2]-Zn-Brook rearrangement owing to its significantly lower activation barrier.
Related Papers
- → DABCO-Catalyzed 1,4-Bromolactonization of Conjugated Enynes: Highly Stereoselective Formation of a Stereogenic Center and an Axially Chiral Allene(2009)128 cited
- → Synthesis of allene triazole through iron catalyzed regioselective addition to propargyl alcohols(2012)47 cited
- → A Study on the Nature of the Allene-ene Intramolecular Cycloaddition Reaction. A Novel Allene-ene Reaction.(1986)1 cited
- → ChemInform Abstract: To Stay as Allene or Go Further? Synthesis of Novel Phosphono‐heterocycles and Polycyclics via Propargyl Alcohols.(2011)
- → ChemInform Abstract: TRANSITION METAL CATALYSIS IN ALLENE FORMATION FROM GRIGNARD REAGENTS AND PROPARGYL CHLORIDES(1978)