Keith P. Parry

Complexation of diquat and paraquat by macrocyclic polyethers incorporating two dibydroxynaphthalene residues

Abstract NMR Spectroscopy and FAB mass spectrometry demonstrate that the 38-crown-10 (1/5DN38C10) and 35-crown-9 (1/5DN35C9) ethers incorporating two 1,5-di-naphtho units form 1:1 complexes with the Paraquat [PQT] 2+ and Diquat [DQT] 2+ dications in solution. In the solid state, the [PQT.1/5DN38C10] 2+ complex is stabilised by face-to-face (π/π charge transfer) interactions between the naphtho and bipyridinium rings, whereas the free 1/5DN35C9 receptor features a classic edge-to-face (H δ+ /π electrostatic) interaction between its two naphtho rings.

Synthesis of carbocyclic clitocine

Abstract Cyclopentadiene has been converted into carbocyclic clitocine (2) in eleven steps.

The self-assembly of a highly ordered [2]catenane

Template-directed synthesis has been used to construct a [2]catenane in which the two molecular components, the cyclobis(paraquat-p-phenylene) tetracation and 1,5-dinaphtho-38-crown-10, are found to be ordered non-covalently with respect to each other in both the solid (by X-ray crystallography) and solution (by NMR spectroscopy) states and to influence each other to the extent of establishing electrochemical gradients for the stepwise one electron reductions of the two paraquat units.

The inhibition of gibberellin plant hormone biosynthesis by ent-6-hydroxy-5β(H)- 7-norgibberell-16-enes

Abstract ent -6α-Hydroxy-5β(H)-7-norgibberell-16-en-19-oic acid and the corresponding diol but not the ent -6β-epimers are shown to be inhibitors of gibberellin biosynthesis at the ring contraction stage and to be potential plant-growth regulators. Their metabolism by Gibberella fujikuroi has been examined.

The preparation of some ent-7-nor-5β-gibberell-16-enes as potential gibberellin biosynthesis inhibitors

Three routes for the preparation of ent-7-nor-5β-gibberell-16-enes from fujenal are described. Evidence is presented for the stereochemistry of the products.

Mimics of intermediates in gibberellin biosynthesis as plant growth regulators

The ring-contracted ent-6α-hydroxy-5β(H)-B-norkaur-16-en-19-oic acid (4) and the corresponding alcohol (6) have been shown to act as inhibitors of gibberellin plant growth hormone biosynthesis at the ring contraction stage and to act as plant growth regulators in rice.

Rearrangement of 2-azabicyclo[2.2.1]hept-5-en-3-ones: synthesis of cis-3-aminocyclopentane carboxylic acid derivatives

The γ-lactam 4 was converted into the bromo ester 6 and the latter compound was transformed in five steps into the diester 10. Similarly the lactam 4 was converted into the hydroxy amide 17via the intermediacy of the dihalogeno compound 11. Compounds 10 and 17 are potential precursors of deoxycarbocyclic nucleosides. Unexpectedly, the lactam 4 furnished the addition product 25 on reaction with benzeneselenenyl bromide and a tentative rationale for the preferred reaction pathway is proposed.

Electrophilic substitution of a 2-azabicyclo[2.2.1]hept-5-en-3-one as a potential route to 3-deoxycarbocyclic nucleosides

The γ-lactam 9 reacted with bromine in the presence of acetic acid or fluoride ion to give the 6,7-substituted 2-azanorbornan-3-ones 10 or 15 respectively. The latter compounds were converted into the cyclopentylamine derivatives 14 and 16 which represent potentially useful precursors for carbocyclic 3-deoxyribonucleosides.

New biosynthetically patterned inhibitors of gibberellin plant hormone formation

ent-19-Hydroxy-7-norgibberella-5,16-diene (13) and the corresponding 19-aldehyde (14) and acid (12), have been prepared from the fungal metabolite, fujenal (8) and shown to act as inhibitors of gibberellic acid biosynthesis in Gibberella fujikuroi and to act as plant growth regulators when tested against rice seedlings.

Chemistry of 2-azabicyclo[2.2.1 ]heptan-3-one derivatives: role of the nitrogen atom in determining the stereochemistry of products isolated after formation of an incipient carbocation at C-6

The nitrogen atom of the amide group is responsible for retention of stereochemistry for the products obtained when the alcohol 6 is allowed to react under Mitsunobu conditions and when 6 is treated with diethylaminosulphur trifluoride.