Joel Myerson

Electrophilic lactonization as a tool in acyclic stereocontrol. Synthesis of serricornin

Abstract Several electrophilic lactonization procedures have been explored as a means of functionalizing olefinic carboxylic acids with relative asymmetric induction, Iodolactonization of δ,ϵ -unsaturated acids under conditions of thermodynamic control exhibits good 1,2- and 1,3-, but not 1,4-induction in the formation of δ-lactones. Mercurilactonization proceeds with good stereocontrol in the formation of both γ- and δ-lactones (1,2-induction), but suffers from the difficulty of elimination during reductive demercuration; phenylselenolactonization with N-(phenylseleno)phthalimide is apparently kinetically controlled, affording high induction with 10 , a strongly sterically biased substrate leading to a δ-lactone, but not with 16 , which leads to a γ-lactone. In contrast, hydroxymethyllactonization proceeds with good stereocontrol in the case of 26 , the ester of 10 , but not with the analogous ester of 16 . The lactones resulting from cyclization of 10 and 13 were converted in stereospecific fashion into each of the stereoisomers of(±)-serricornin.

Streamlined process for the chemical synthesis of RNA using 2'-O-thionocarbamate-protected nucleoside phosphoramidites in the solid phase

An improved method for the chemical synthesis of RNA was developed utilizing a streamlined method for the preparation of phosphoramidite monomers and a single-step deprotection of the resulting oligoribonucleotide product using 1,2-diamines under anhydrous conditions. The process is compatible with most standard heterobase protection and employs a 2-O-(1,1-dioxo-1λ(6)-thiomorpholine-4-carbothioate) as a unique 2-hydroxyl protective group. Using this approach, it was demonstrated that the chemical synthesis of RNA can be as simple and robust as the chemical synthesis of DNA.

Top-down design for a system to control operant choice experiments

STATIONS, a FORTRAN program to control operant choice experiments, was developed based on the principles of top-down design and structured programming. As a consequence, the program consists of modules organized in a hierarchical fashion. Separate modules deal with different types of reinforcement schedules, such as variable ratio (VR) and variable interval (VI). These modules produce specific schedules with different parameters by using sequences of values read in at ran time and then randomly sampled. This form of organization permits modifications to be made via changes confined to one module without global repercussions. The clarity of structure that results from the application of top-down design and structured programming should enable future users to more easily adapt this package to suit their specific needs.