Kinetic relationship in parallel autocatalytic amplifications of pyridyl alkanol and chiral trigger pyrimidyl alkanol.

Experimental and kinetic analysis of a chemical system combines autocatalytic amplification of 2-alkynyl-5-pyrimidyl alkanol 2 and 6-alkynyl-3-pyridyl akanol 4 in which 2 acts as a chiral trigger and 4 being the subsequent autocatalyst. Starting from a very low initial ee, both alkanols are produced with high enantiopurity in one single cycle. This provides insight into a dual nonlinear amplification of chirality observed with amplifying trigger 2 and accelerated amplification of autocatalyst 4. These kinetic studies reveal a five-fold magnitude superior amplification rates of 4 associated with trigger's enantiopurity at the outset.

Asymmetric Autocatalysis as a Relay for Remote Amplification of Chirality of Target Molecules Used as Triggers.

Nearly racemic target molecules are enantiomerically enriched through an asymmetric autocatalytic relay for a remote amplification of chirality. Target alkynols with very low initial ee act as chiral triggers for asymmetric amplification of the Soai autocatalyst, which in turn enables the formation of the same alkynols with greater enantiomeric purity. Additionally, the stereochemical correlation between the trigger/target and autocatalyst molecules is discussed.

Synthesis of the A-D Ring System of the Gambieric Acids.

The A-D fragment of gambieric acids A and C has been synthesized using an asymmetric Tsuji-Trost allylation reaction to couple the two key segments. The A ring fragment has been prepared by a short and highly efficient route involving diastereoselective Lewis acid mediated alkylation of an acetal. Iterative ring-closing metathesis reactions have been used to construct cyclic ethers and assemble the tricyclic B-D fragment.