T. Howard Black

Lactone synthesis via dyotropic rearrangement. Stereospecific construction of fused butyrolactones with three contiguous asymmetric centers

Abstract Substituted trans-fused cyclohexano butyrolactones are accessible via dyotropic rearrangement of β-lactones, wherein all three adjacent chiral centers are simultaneously fixed.

Synthesis of cyclic and acyclic βγ-unsaturated car☐ylic acids Via an E1-type ionization/elimination of β-lactones

Abstract Cyclic and acyclic ketones were converted in three steps into 3-alkenoic acids, bearing a variety of substituents in the α -position. The sequence, involving ionization/elimination of a β-lactone, affords high yields of pure products uncontaminated with conjugated isomers. Support for an El-type mechanism is also provided.

A facile 3-alkyl butenolide annulation sequence

Abstract Spiro 3-alkyl 3-chloro oxetan-2-ones, derived from cycloalkanones, rearrange under the influence of Lewis acids to ring-fused alkyl butenolides.

Carbonyl Homologation via β-Trimethylsilyl β-Lactone Rearrangements. A Nonbasic Alternative to the Wittig Reaction

Abstract Saturated and unsaturated aldehydes and ketones, when treated with trimethylsilylketene and BF3 for 16 hours, form β-lactones which spontaneously rearrange to α,β-unsaturated TMS esters; these hydrolyze during workup to form the corresponding carboxylic acids.

A new synthesis of substituted spiro butyrolactones via dyotropic rearrangement

Abstract Spiro butyrolactones bearing various α-substituents have been synthesized in three steps from acetic acid derivatives; the sequence employs a dyotropic rearrangement as its pivotal step.

A Versatile Synthesis of 3-Substituted 5-Alkyl Butyrolactones Via Dyotropic Rearrangement

Abstract Substituted acetic acid dianions are convertable to to 3,5-disubstituted butyrolactones, employing a dyotropic rearrangement as the key step.

An efficient, highly regioselective synthesis of substituted (1-cyclohexenyl) acetic acid derivatives via ionization/elimination of β-lactones

Abstract When treated with magnesium bromide, spiro β-lactones undergo an ionization/elimination reaction to afford cyclohexenyl acetic acid derivatives in high yield and isomeric purity.

A new synthesis of substituted butenolides via cation-initiated ring expansion/elimination of β-lactones

Abstract When treated with silver ion, γ-bromo β-lactones, available via bromolactonization, undergo a ring expansion/elimination reaction to afford substituted butenolides.

A novel oxygen-to-carbon ester migration catalysed by 4-(N,N-dimethylamino)-pyridine in the benzofuranone ring system

4-(N,N-Dimethylamino)pyridine (DMAP) promotes the quantitative rearrangement of benzofuranone-derived enol carbonates to the corresponding carbon-acylated isomers.

A Rapid, Nearly Quantitative Conversion of Codeine to Hydrocodone

Abstract A very rapid, two-step, virtually quantitative synthesis of hydrocodone from codeine, via the intermediacy of dihydrocodeine, has been developed.