A simple synthetic autocatalytic replicator is capable of establishing and driving the propagation of a reaction-diffusion front within a 50 μL syringe. This replicator templates its own synthesis through a 1,3-dipolar cycloaddition reaction between a nitrone component, equipped with a 9-ethynylanthracene optical tag, and a maleimide. Kinetic studies using NMR and UV-vis spectroscopies confirm that the replicator forms efficiently and with high diastereoselectivity, and this replication process brings about a dramatic change in optical properties of the sample-a change in the color of the fluorescence in the sample from yellow to blue. The addition of a small amount of the preformed replicator at a specific location within a microsyringe, filled with the reaction building blocks, results in the initiation and propagation of a reaction-diffusion front. The realization of a replicator capable of initiating a reaction-diffusion front provides a platform for the examination of interconnected replicating networks under out-of-equilibrium conditions involving diffusion processes.

The emergence of collections of simple chemical entities that create self-sustaining reaction networks, embedding replication and catalysis, are cited as potential mechanisms for the appearance on the early Earth of systems that satisfy minimal definitions of life. In this work, a functional reaction network that creates and maintains a set of privileged replicator structures through auto-and cross-catalyzed reaction cycles is created from the pairwise combinations of four reagents. We show that the addition of individual pre-formed templates to this network, representing instructions to synthesize a specific replicator, induces changes in the output composition of the system that represent a network-level response. Further, we establish through sets of serial transfer experiments that the catalytic connections that exist between the four replicators in this network and the system-level behavior thereby encoded impose limits on the compositional variability that can be induced by repeated exposure to instructional inputs, in the form of preformed templates, to the system. The origin of this persistence is traced through kinetic simulations to the properties and interrelationships between the critical ternary complexes formed by the auto-and crosscatalytic templates. These results demonstrate that in an environment where there is no continuous selection pressure, the network connectivity, described by the catalytic relationships and system-level interactions between the replicators, is persistent, thereby limiting the ability of this network to adapt and evolve.

Fused pyridine derivatives R 0450Gold Catalysis: Switching the Pathway of the Furan-Yne Cyclization. -A new class of tetracyclic systems is synthesized under very mild conditions. The method is also successfully applied to a non-heterocyclic substrate (XI) with a prenyl side-chain which is converted into heterocycle (XII). -(HASHMI*, A. S. K.; RUDOLPH, M.; HUCK, J.; FREY, W.; BATS, J. W.; HAMZIC, M.; Angew.