This Review describes the basic concepts that have guided our exploration of new chemical reactions by giving examples of results from my research group. Our strategy of carrying out research is to investigate three to four different topics at a time so we can gather as many results as possible. These may at first appear unrelated to each other but may have the potential to be united into a greater hypothesis after repeated feedback. Three scenarios from our research are presented: the "oxidative-reductive condensation reaction" devised in 1960, which after an interval of nearly 40 years brought forth the new concept of using compounds of structure Ph(2)POR as reducing reagents; the "TiCl(4)-aldol reaction" of 1973 that eventually led to the present "base-promoted aldol reaction" through a chain of ideas; and the "glycosylation reaction using fluorosugars" from 1984 which recently bloomed into "stereocontrolled glycosylation". Thus, it can be said that by reviewing what we had done before, we were able to expand on it to achieve new outcomes.

Explorations into new reaction chemistry.

Topics concerning the cationic ring-opening polymerization of cyclic imino ethers and functional material production based on the resulting polymers are reviewed. Cyclic imino ethers are readily subjected to isomerization polymerization via cationic initiators. Mechanistic studies have provided a new concept, electrophilic polymerization. Double isomerization polymerization and no-catalyst alternating copolymerization are interesting examples that show characteristics of the ring opening of cyclic imino ethers. The living polymerization of these monomers affords precisely controlled polymeric materials. Through the use of the unique properties of the product polymers, various functional polymeric materials, such as polymeric nonionic surfactants, compatibilizers, hydrogels, stabilizers for dispersion polymerization, biocatalyst modifiers, and supramolecular assemblies, have been developed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 192–209, 2002

https://onlinelibrary.wiley.com/doi/pdf/10.1002/pola.10090

Polymerization of cyclic imino ethers: From its discovery to the present state of the art

The polyaddition of 4,4′-bis[(3-ethyl-3-oxetanyl)methoxy]biphenyl (4,4′-BEOBP) and phenylphosphonic dichloride (PPDC) with quaternary onium salts as catalysts proceeded under mild reaction conditions to afford a polymer containing phosphorous atoms in its main chain. A polyphosphonate with a high number-average molecular weight (10,300) was obtained by the reaction of 4,4′-BEOBP and PPDC in the presence of tetraphenylphosphonium chloride (TPPC) in o-dichlorobenzene at 130 °C for 24 h. The structure of the resulting polymer was confirmed with IR, 1H NMR, and 31P NMR spectroscopy. Furthermore, it was proved that the polyaddition of certain bis(oxetane)s with phosphonic dichlorides proceeded smoothly to give corresponding polyphosphonates with TPPC as the catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3835–3846, 2002

Synthesis of polyphosphonates containing pendant chloromethyl groups by the polyaddition of bis(oxetane)s with phosphonic dichlorides

Durch Umsetzung von achiralen Phosphonigsaurediamiden RP(NMe2)2 mit chiralen Aminoalkoholen wie L-Ephedrin und L-Prolinol werden die entsprechenden methyl- und phenylsubstituierten mono- (2, 3) bzw. bicyclischen 1,3,2-Oxazaphospholidine (6 – 8) in guten Ausbeuten erhalten. Dagegen lassen sich Oxazaphospholidine unter Verwendung von Phosphonigsauredichloriden nur fur R = tert-Butyl (4, 5) herstellen. Die Diastereomerenreinheit der Ephedrin-und der Prolinol-Derivate betragt zwischen 80% fur R = Methyl und 95% d.e. fur R = tert-Butyl. Fur das Bis-1,3,2-oxazaphospholidin 8 aus 2 Molekulen Prolinol und 1 Molekul 1,2-Ethandiylbis-[bis(dimethylamino)phosphan] last sich NMR-spektroskopisch kein weiteres Diastereomeres mehr nachweisen. Durch Analyse der 13C-31P- und 1H-31P-Kopplungskonstanten wird den Ephedrin-Derivaten die (2S,4S,5R)- und den Prolinol-Derivaten die (2R,5S)-Konfiguration zugeordnet.



Asymmetric Synthesis of 2-Organo-1,3,2-oxazaphospholidines



Achiral organophosphonous diamides RP(NMe2)2 react with chiral amino alcohols such as L-ephedrine and L-prolinol to form methyl- and phenyl-substituted mono- (2, 3) and bicyclic 1,3,2-oxazaphospholidines (6 – 8) in good yields. Organophosphonous dichlorides allow the synthesis of oxazaphospholidines only for R = tert-butyl (4, 5). The diastereomeric excess of the ephedrine and prolinol derivatives ranges from 80% (R = methyl) to 95% d.e. (R = tert-butyl). The bis-1,3,2-oxazaphospholidine 8, made from two mols of prolinol and one mol of 1,2-ethanediylbis[bis(dimethylamino)phosphane], is virtually diastereomerically pure according to the NMR spectrum. Analysis of the 13C-31P and 1H-31P coupling constants affords the structural assignment of the ephedrine derivatives as (2S,4S,5R) and the prolinol derivatives as (2R,5S).

Asymmetrische Synthese von 2‐Organo‐1,3,2‐oxazaphospholidinen

Strategien zur Erforschung neuer Reaktionen

1,3-Addition-Type Ring-Opening Polymerization of Cyclic Phosphonites

As one of a series of studies of 1,4-addition type ring-opening polymerizations, the synthesis and ring-opening polymerization of N-substituted cyclic iminocarbonates have been studied. N-Alkyl and N-aryl cyclic iminocarbonates have been prepared by the reaction of sodium ethylene glycorate with the corresponding imidophosgenes. N-Halogeno cyclic iminocarbonates have been prepared from glycols, potassium cyanide and halogenes. The ring-opening polymerization of the N-substituted cyclic iminocarbonates, which are considered to be cyclic enol derivatives of urethanes, in the presence of cationic catalysts gives the corresponding poly(ethylene N-substituted carbamates).

The Synthesis and 1,4-Addition Type Ring-opening Polymerization of N -Substituted Cyclic Iminocarbonates

The rate constants, the activation energies and the entropies of the activation of the ring-opening addition reactions of exo-imino cyclic compounds, such as ethylene N-phenyliminocarbonate, 2-phenylimino-3-methyloxazolidine and N-substituted 2-iminotetrahydrofurans, with carboxylic acids in various solvents have been determined in order to study the mechanism of these reactions. The rate of the reactions increases as the acidity of carboxylic acids increases, and the linear Hammett relation is observed in the reactions of ethylene N-phenyliminocarbonate or 2-phenylimino-3-methyloxazolidine with meta- and para-substituted benzoic acids. The relative rate of the reactions of the three exo-imino cyclic compounds, ethylene N-phenyliminocarbonate, 2-phenylimino-3-methyloxazolidine and 2-phenyliminotetrahydro-furan, with carboxylic acids is as follows: (Remark: Graphics omitted.) These results show that the ring-opening addition reaction involves two stages, namely, the initial formation of the intermediate sa...

Yorikazu Tamura

Papers

1,3-Addition-Type Ring-Opening Polymerization of Cyclic Phosphonites

The Synthesis and 1,4-Addition Type Ring-opening Polymerization of N -Substituted Cyclic Iminocarbonates

The Ring-opening Addition Reactions of Exo-imino Cyclic Compounds with Carboxylic Acids