Gregory Roos

Asymmetric synthesis in carbon–carbon bond forming reactions of α-diazoketones catalysed by homochiral rhodium(II) carboxylates

Partial asymmetric synthesis has been observed in intramolecular C–H insertion, aromatic cycloaddition, and cyclopropanation reactions of α-diazoketones catalysed by homochiral rhodium(II) mandelate and rhodium(II) carboxylates derived from L-proline.

The syntheses of (±)-juglomycin A and (±)-juglomycin B, racemates of two isomeric naturally occurring naphthoquinonoid antibiotics

Syntheses of the diastereoisomeric 5-hydroxy-2-(4′-hydroxy-γ-butyrolacton-5′-yl)-1,4-naphthoquinones (1) and (2) and their 5-deoxy-analogues (3) and (4) are described. The stereochemistries of the latter, being defined through unambiguous synthesis, permit the assignment of the configurations of (1) and (2)(which were obtained from a single precursor) and also those of the natural products, juglomycins A and B.

Syntheses of the naturally occurring naphtho[2,3-b]pyran-5,10-quinones α-caryopterone, dihydro-α-caryopterone, and O-methyldihydro-α-caryopterone

The title compounds have been prepared by appropriate alkylation of 3-hydroxy-5-methoxy-1,4-napthoquinone, obtained from the adduct (6) derived by addition of 1-methoxycyclohexa-1,3-diene (4) to 2-methoxy-1,4-benzoquinone (5).

A novel method for the N-acylation of (4R,5S)-1,5-dimethyl-4-phenylimidazolidin-2-one

Abstract An efficient synthesis of N -Acylimidazolidinones derived from α,β-unsaturated acid chlorides using DABCO as the base is described.

Enantioselective Approaches to Rhodium Catalysed Aldol-Type Reactions

Abstract Homochiral catalysts, [Rh (norbornadiene)-(homochiral diphosphine)]+ X−/H2, were tested to assess possible enantiocontrol in the aldol-type coupling of activated vinyl components with aldehydes. A related approach, via in situ rhodium silyl enolates, was also investigated.

Approach to the synthesis of (+)-Ifforestine. Model studies directed at the tetracyclic framework

In order to design an effective asymmetric synthesis of (+)-ifforestine, model approaches to the construction of the tetracyclic ring system have been investigated. These studies have identified two key synthons, a functionalized isatoic anhydride and a pipecolic acid derivative, as suitable AB- and D-ring portions for creation of the crucial diazopinedione C-ring.

Syntheses of substituted 1,4-naphthoquinones by Diels–Alder addition of methoxycyclohexadienes to substituted 1,4-benzoquinones

Additions of 1-methoxycyclohexa-1,3-diene to 2-methoxy-3-methyl-1,4-benzoquinone and to chloro-1,4-benzoquinone give Diels–Alder adducts which are coverted in high yield into substituted juglone methyl ethers. Reactions between 1-methoxy-3-methylcyclohexa-1,3-diene and methoxy-1,4-benzoquinone follow a similar course. Addition of 1,3-dimethoxycyclohexa-1,3-diene to chloro- or methoxy-benzoquinone affords a dihydrodibenzofuran rather than a Diels–Alder adduct.

An expedient route to the glycine templates (R)- or (S)-N-Cbz-5-phenyl-1,4-oxazin-2-one

An economical and practical route to the title compounds is described. The three step, essentially “one pot” sequence proceeds in overall yields of up to 80% without the need for chromatography or intermediate isolation.

A facile route to some useful homochiral alkyl Imidazolidin-2-one-4(S)-carboxylates

A general, high yielding route to optically pure alkyl 1 N-alkyl and 1 N-acyl substituted imidazolidin-2-one-4(S)-carboxylates, with diverse potential uses in asymmetric synthesis, is reported.

Syntheses of isobenzofuran-4,7-quinone and isoindole-4,7-quinone

The syntheses of the title compounds via the 1,4-epoxy-(9) and 1,4-imino-(21) 5,8-naphthoquinones are described.