Janice M. Nelke

Bio: Janice M. Nelke is an academic researcher from Monsanto. The author has contributed to research in topics: Acyloin condensation & Cyclobutene. The author has an hindex of 3, co-authored 4 publications receiving 48 citations.

The acyloin condensation. Synthesis of a [4,2,2]-propellane (tricyclo[4,2,2,01,6]decane)1 derivative

Abstract: Acyloin condensation of dimethyl bicyclo-[4,2,0]octane-1,6-dicarboxylate in the presence of chlorotrimethylsilane produces 7,8-bis(trimethylsilyloxy)-[4,2,2]propell-7-ene (25–40%) and the bis-(trimethylsilyloxy)-dimethoxy-keten acetal of 1,4-cyclo-octane dicarboxylate (40–58%); solvolysis of the propellane in weakly acidic methanol gave 1-methoxy-8-hydroxybicyclo[4,2,2]decane-7-one by apparent homoconjugate attack at the central carbon–carbon bond.

Acyloin Condensation in which Chlorotrimethylsilane is used as a Trapping Agent: 1,2‐Bis(trimethylsilyloxy)cyclobutene and 2‐Hydroxycyclobutanone

Abstract: Acyloin condensation in which chlorotrimethylsilane is used as a trapping agent: 1,2-bis(trimethylsilyloxy)cyclobutene and 2-hydroxycyclobutanone product: 1,2-Bis(trimethylsilyloxy)cyclobutene product: 2-hydroxycyclobutanone Keywords: coupling; cyclization, reductive cyclization; reduction, miscellaneous; chlorotrimethylsilane, drying of; sodium sand; sodium-potassium alloy; toluene; chlorotrimethylsilane, in acyloin reactions; sodium-potassium alloy; addition funnels, Hershberg; dry-box, in the preparation of 2-hydroxycyclobutanone; stirrers, vibromixer; vibromixer

The Acyloin Condensation

Abstract: The acyloin condensation usually involves the reductive dimerization of a carboxylic ester, although acid chlorides and the anhydrides have been used. The reducing agent is in an alkali metal and the product is an ene-diolate. Two gram-atoms of metal are required for each mole of ester with the concomitant formation of a mole of akoxide and one-half mole of the ene-diolate. Oxidation of acyloins to diketoes can be accomplished by a variety of reagents. Acyloins can be reduced to ketones by various modifications of the Clemmenson technique. Under mild conditions the ketone will dominate. This chapter presents a complete picture of both the linear and cyclic acyloin condensation with particular emphasis on developments since 1960. The discussion is closely limited to the acyloin condensation and its modifications. Keywords: condensation; acyloin; dicarboxylic acids; monocarboxyl acids; reduction; oxalates; malonates; succinates; glutarates; adipates; pimelates; heterocyclic esters; esters; ketone; semidiones; experimental procedures

Enantioselective Synthesis of Optically Active Pyridine Derivatives and C2-Symmetric 2,2′-Bipyridines

Abstract: Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 are obtained by enantioselective reduction of the corresponding ketones 5, 7, 11–13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl]. Nickel(0)-mediated coupling of bromopyridines 2, 15, and 31 gives C2-symmetric 2,2′-bipyridines (R,R)-32, (R,R′)-33, and (S,S)-38, respectively, which form metal complexes with CoII, PdII, CuI, and AgI. Aryl-substituted pyridines 26, and 39–41 are synthesized by palladium(0)-catalyzed cross couplings of 2 and 15 with boronic acids 42–44.

Cyclo[m]pyridine[n]pyrroles: hybrid macrocycles that display expanded π-conjugation upon protonation.

Abstract: Novel hybrid cyclo[m]pyridine[n]pyrroles have been synthesized using Suzuki coupling. Their NMR and optical spectroscopic features and solid state structural parameters provide support for the proposal that these species are best described as locally aromatic compounds devoid of long-range intersubunit conjugation. However, an extension of the π-conjugation in the macrocycles can be realized through protonation, as inferred from optical spectroscopic and X-ray diffraction-based structural studies.