ABSTRACT
Soft scorpionates have thus far been seen mainly as a family of ligands. Their chemistry is extended here to the production of novel cationic macrocycles using dihaloalkanes. By replacing the dihaloalkanes with mild oxidising agents (NO(+), I2) we obtain two unique polycyclic heterocycles. The mechanism which leads to the formation of these polycyclic heterocycles is investigated using ab initio DFT calculations.
ABSTRACT
The first total synthesis of Cleistenolide, a novel natural product recently isolated from the Annonaceae species Cleistochlamys kirkii Oliver, is described. The synthesis proceeds in six steps and 18% overall yield, starting from an enantiopure C2-symmetric building block and using a Sharpless epoxidation, a selective epoxide opening, and a ring-closing metathesis reaction.
Subject(s)
Epoxy Compounds/chemistry , Pyrones/chemical synthesis , Annonaceae/chemistry , Cyclization , Magnetic Resonance Spectroscopy , Molecular Structure , Pyrones/chemistry , StereoisomerismABSTRACT
Protected 3,6-dideoxyglycals have been synthesized de novo as single isomers starting from ethyl lactate by using the tandem RCM-isomerization reaction as the key step. Different relative configurations become accessible by addition of vinyl- or allyl-metal compounds to protected lactaldehydes under Cram-chelate or Felkin-Anh control. The concept is exemplified for glycals of L-rhodinose and L-amicetose, as well as for ring-expanded non-natural analogues thereof. This novel approach to glycals is also applicable to the synthesis of disaccharide glycals via a reiterative strategy, as exemplified for the dimer of L-rhodinose and its non-natural ring expanded analogue.
Subject(s)
Oxygen/chemistry , Polysaccharides/chemistry , Isomerism , Molecular StructureABSTRACT
Ring closing metathesis and tandem RCM-isomerization have been applied to the synthesis of six- to eight-membered oxacycles, starting from a common precursor. The products of the tandem RCM-isomerization sequence are glycals of 3-deoxyheptoses of varying ring size.
Subject(s)
Ethers, Cyclic/chemical synthesis , Heptoses/chemistry , Cyclization , Ethers, Cyclic/chemistry , Molecular Structure , StereoisomerismABSTRACT
The synthesis and structure of two related sodium complexes are reported which demonstrate that sulfur can preferentially complex to sodium irrespective of the presence of more apposite donor species such as DMF.
