Deborah A. Longbottom

MULTI-STEP ORGANIC SYNTHESIS USING SOLID-SUPPORTED REAGENTS AND SCAVENGERS: A NEW PARADIGM IN CHEMICAL LIBRARY GENERATION

1 Review 1.1 Overview 1.2 Solid-phase organic synthesis (SPOS) 1.3 Beyond conventional solid-phase organic synthesis 1.4 The review 1.5 Some definitions 1.6 Solid-supported reagents and scavengers 1.7 Multi-step use of solid-supported reagents and scavenging reagents 1.8 Conclusions and future perspective 2 Introduction to the tables 2.1 Organisation of tables (reagent and catalyst section) 2.2 Representative data entry (reagent and catalyst section) 2.3 Organisation of tables (scavenging agents section) 2.4 Representative data entry (scavenging agents section) 3 Tables of reagents and catalysts 4 Tables of scavengers 5 Other relevant reviews 5.1 Insoluble polymers 5.1.1 Structure and physical properties (insoluble polymers) 5.1.2 General (insoluble polymers) 5.1.3 Reactions (insoluble polymers) 5.1.4 Miscellaneous (insoluble polymers) 5.2 Soluble polymers 5.2.1 General (soluble polymers) 5.2.2 Reactions (soluble polymers) 5.3 Inorganic solids 5.3.1 Structure and physical properties (inorganic solids) 5.3.2 General (inorganic solids) 5.3.3 Reactions (inorganic solids) 5.3.4 Miscellaneous (inorganic solids) 5.4 Miscellaneous supports 5.4.1 Structure and physical properties (miscellaneous supports) 5.4.2 General (miscellaneous supports) 5.4.3 Reactions (miscellaneous supports) 5.4.4 Miscellaneous (miscellaneous supports) 5.5 Purification strategies 5.5.1 Various supports (purification strategies) 5.5.2 Insoluble polymers (purification strategies) 6 Acknowledgements 7 Abbreviations 8 References 1 Review

Aldol reactions catalyzed by L-proline functionalized polymeric nanoreactors in water

The use of functional core-shell micelles as asymmetric catalytic nanoreactors for organic reactions in water is presented. An unprecedented increase in rate of reaction was achieved, which is proposed to be associated with the ability of the nanostructures to effectively concentrate the reagents in the catalytically active micelle core.

Tuning the catalytic activity of L-proline functionalized hydrophobic nanogel particles in water

L-Proline functionalized PMMA nanogels with a range of catalyst functionalization (0.5–15 wt%) and cross-linking densities (0–50 wt%) were prepared via emulsion polymerization. The catalyst efficiency in water was investigated using a model asymmetric aldol reaction and an unprecedented reduction in catalyst loading, whilst maintaining high catalytic activity, is reported. In these reactions, a marked effect on selectivity was observed and determined to be dependent on the hydrophobicity of the nanogel particles. Furthermore, the effect of increasing cross-linking density on the catalytic efficiency of these particles (and their core–shell analogues) was explored and a significant reduction in activity was observed.

A sequential enantioselective, organocatalytic route to chiral 1,2-oxazines and chiral pyridazines

A sequential, organocatalysed asymmetric reaction to access chiral 1,2-oxazines and chiral pyridazines is reported, which proceeds in moderate to good yields and good to excellent enantioselectivities.

A new asymmetric organocatalytic nitrocyclopropanation reaction

Using 5-(pyrrolidin-2-yl)-1H-tetrazole as an organic catalyst, the nitrocyclopropanation of 2-cyclohexen-1-one has been achieved, proceeding in high yield and with good enantioselective control.

Total synthesis of the polyenoyltetramic acid polycephalin C

The total synthesis of the polyenoyltetramic acid polycephalin C is described. Key steps of the synthesis include a double Swern oxidation, double Takai reaction and a double Stille reaction. In addition, the absolute stereochemistry of the ring junction has been determined by synthesis of both isomers and comparison of their CD spectra with natural polycephalin C.

Immobilization of MacMillan catalyst via controlled radical polymerization: catalytic activity and reuse

The MacMillan catalyst is an established organocatalyst capable of catalyzing a variety of organic reactions. Through the synthesis of a novel monomer containing the MacMillan catalytic functionality, a variety of copolymers have been synthesized with the comonomer, diethylene glycol methyl ether methacrylate (DEGMA). Reversible addition–fragmentation chain transfer (RAFT) polymerization was used for the synthesis of these functional polymers with good control over molecular weight, catalyst incorporation and polydispersity. These polymers showed lower critical solution temperature (LCST) behaviour where the cloud point was found to be dependent upon the degree of catalyst incorporation and catalyst loading was also found to have an effect on the Tg of the copolymers. The catalytic activity of the functional copolymers is demonstrated by the Diels–Alder reaction between cyclopentadiene and trans-hexen-1-al and shows enantioselectivity close to those previously reported by MacMillan. The polymers can be reused in multiple Diels–Alder reactions via a pseudo continuous process, maintaining high conversion and enantioselectivity throughout the cycles.

Highlights from the 40th EUCHEM Conference on Stereochemistry, Bürgenstock, Switzerland, April 2005

‘ Where most see a wall, some see a door and a few go through to discover a rich, new world......open sesame! ’

Total synthesis of the plasmoidal pigment physarorubinic acid, a polyenoyl tetramic acid

The total synthesis of physarorubinic acid, a polyenoyltetramic acid plasmoidal pigment from Physarum polycephalum, is described in a series of steps from (E)-3-iodoacrylic acid 6 and employs aminolysis of the pentaene thioester 11 as a key synthetic step. Lacey–Dieckmann cyclisation and subsequent deprotection then affords physarorubinic acid 1 in high yield and purity.