Catalytic enantioselective allylation of carbonyl compounds and imines.

The alternating copolymerization of (R)- or (S)-limonene oxide and CO2 using beta-diiminate zinc acetate catalysts is reported. At 100 psi CO2 and 25 degrees C, the catalyst exhibits a high selectivity for the trans isomer and produces regioregular polycarbonate. The copolymer contains >99% carbonate linkages, a narrow molecular weight distribution, and an Mn value consistent with the [epoxide]/[Zn] ratio.

Alternating copolymerization of limonene oxide and carbon dioxide.

Organoindium reagents: the preparation and application in organic synthesis.

A quest for polycarbonates provided via sustainable epoxide/CO2 copolymerization processes

Phosphorothioate nucleotides have emerged as powerful pharmacological substitutes of their native phosphodiester analogs with important translational applications in antisense oligonucleotide (ASO) therapeutics and cyclic dinucleotide (CDN) synthesis. Stereocontrolled installation of this chiral motif has long been hampered by the systemic use of phosphorus(III) [P(III)]–based reagent systems as the sole practical means of oligonucleotide assembly. A fundamentally different approach is described herein: the invention of a P(V)-based reagent platform for programmable, traceless, diastereoselective phosphorus-sulfur incorporation. The power of this reagent system is demonstrated through the robust and stereocontrolled synthesis of various nucleotidic architectures, including ASOs and CDNs, via an efficient, inexpensive, and operationally simple protocol.

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Unlocking P(V): Reagents for chiral phosphorothioate synthesis

cis- and trans-Diastereomers of (R)-(+)-limonene oxide can be purified by simple kinetic separation of the commercially available (1:1) diastereomeric mixture of limonene oxides. Nucleophilic amines, such as pyrrolidine and piperidine, selectively open the epoxide ring of the trans-isomer, leaving the cis-limonene oxide largely unreacted. The unreacted cis-(R)-limonene oxide is recovered in up to 88% yield. On the other hand, less nucleophilic amines, such as triazole or pyrazole, selectively catalyze hydrolysis of the cis-limonene oxide to 1,2-limonene diol leaving the trans-limonene oxide largely unreacted. The unreacted trans-limonene oxide is recovered in up to 80% of the theoretical yield by a simple workup procedure. The cis- and trans-diastereomers of (R)-(+)-limonene oxide thus isolated were found to be >98% pure by both GC and NMR analyses. Thus, depending on the choice of amine, either cis- or trans-limonene oxide may be obtained in high diastereomeric purity by this simple and environmentally friendly method.

A facile and efficient method for the kinetic separation of commercially available cis- and trans-limonene epoxide

A series of β-amino alcohols, conveniently prepared from limonene oxide, were evaluated as catalysts for the enantioselective addition of dialkylzinc to benzaldehyde. These limonene-based amino alcohols are of particular interest because they are easily synthesized in both enantiomeric forms. Ethylation of benzaldehyde using diethylzinc and catalyzed by limonene derived amino alcohols proceeded with enantioselection of up to 87% ee. This is an unusually high level of induction for amino alcohols possessing a trans relationship between the amino and alcohol functionalities. Both enantiomers of 1-phenyl-1-propanol can be synthesized with equal control since both enantiomers of the chiral catalyst are readily available. When (1S,2S,4R)-limonene amino alcohols are used as chiral catalysts, (R)-1-phenyl-1-propanol is obtained as the major product. A plausible mechanism is proposed to explain the facial selectivity determining the asymmetric induction observed in these reactions.

Asymmetric addition of diethylzinc to aldehydes catalyzed by β-amino alcohols derived from limonene oxide

Indium-mediated Barbier-type allylation of aldehydes as a convenient method for the highly enantioselective synthesis of homoallylic alcohols

Scale-Up of the Preparation of (1R,2R,4S)-1-Methyl-4-(1-methylethenyl)-2-(4-morpholinyl)cyclohexanol§

Targeted molecular bar codes and methods for using the same are provided. The subject targeted molecular bar codes include a molecular bar code and a member of a specific binding pair, where the specific binding pair member is generally bonded to the bar code through a linking group. The subject molecular bar code may be read during translocation through a single nano-meter scale pore. The subject targeted molecular bar codes find use in a variety of different applications involving analyte detection, such as screening and diagnostic applications.

Derek Steiner

Papers

A facile and efficient method for the kinetic separation of commercially available cis- and trans-limonene epoxide

Asymmetric addition of diethylzinc to aldehydes catalyzed by β-amino alcohols derived from limonene oxide

Indium-mediated Barbier-type allylation of aldehydes as a convenient method for the highly enantioselective synthesis of homoallylic alcohols

Scale-Up of the Preparation of (1R,2R,4S)-1-Methyl-4-(1-methylethenyl)-2-(4-morpholinyl)cyclohexanol§

Targeted molecular bar codes