New boron(III)-catalyzed amide and ester condensation reactions

In 1996, we reported that benzeneboronic acids bearing electron-withdrawing groups at the meta- or para-position are highly effective catalysts for the amide condensation reaction in less-polar solvents. In this paper, we report that N-alkyl-4-boronopyridinium halides are more effective catalysts than the previous ones in more polar solvents. N-Alkyl-4-boronopyridinium halides are effective not only for amide condensation between equimolar mixtures of carboxylic acids and amines but also for the esterification of α-hydroxycarboxylic acids in alcohol solvents. Furthermore, perchlorocatecholborane is more effective than areneboronic acids for the amide condensation of sterically demanding carboxylic acids. In addition, Lewis acid-assisted Brønsted acid (LBA), which is prepared from a 1:2 M mixture of boric acid and tetrachlorocatechol, is effective for the Ritter reaction from alcohols and nitriles to amides.     

Morphological and spectroscopic properties of thin films of self-assembling amphiphilic porphyrins on a hydrophilic surface as revealed by scanning near-field optical microscopy

We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties.     

First total syntheses of the phytotoxins solanapyrones D and E via the domino Michael protocol

The phytotoxins solanapyrones D (1) and E (2) have been synthesized from the decalone prepared by the domino Michael reaction of the kinetic enolate of optically pure acetylcyclohexene with methyl crotonate. The decalone was transformed into a solanapyrone core by equilibration into thermodynamically stable trans-decalone (11), dehydroxylation, and dehydration. Condensation of a methyl acetoacetate equivalent followed by cyclization installed a pyrone moiety. Introduction of a formyl or hydroxymethyl unit into the pyrone ring via Pummerer related reactions furnished solanapyrones D (1) and E (2).     

Structures of new aromatics glycosides from a Japanese folk medicine, the roots of Angelica furcijuga

Three new aromatics glycosides, hyuganosides II, IIIa, and IIIb, were isolated from a Japanese folk medicine, the roots of Angelica furcijuga KITAGAWA. The structures of the new glycosides were determined on the basis of chemical and physicochemical evidence.     

Silver(I) compounds consisting of [2.2]paracyclophane: reversible guest-driven solid-state transformation and incorporation behavior

Reaction of [2.2]paracyclophane with silver(I) heptafluorobutyrate (AgC3F7CO2) has isolated three novel networks: [Ag4(pcp)(C3F7CO2)4] x pyrene (1), [Ag4(pcp)(C3F7CO2)4] x phen (phen = phenanthrene) (2), and [Ag4(pcp)(C3F7CO2)4] x fluorene (3), and an intercalation compound [Ag4(pcp)(C3F7CO2)4] x 2benzene (4). All the four complexes exhibit two-dimensional (2D) sheet structures in which AgC3F7CO2 form an infinite chain and pcp acts as linkage. 1, 2, and 3 show 2D flat sheets with cavities in which guest molecules are situated, whereas 4 exhibits 2D zigzag layers between which guest benzene molecules are intercalated. Pcp shows mu-di-eta1-eta2 coordination mode in 1, mu-tetra-eta1 coordination mode in 2 and 3, and mu-tetra-eta2 coordination mode in 4. The reversible guest exchanges were observed between complex 1, 2, or 3 and intercalation compound 4. It is unprecedented for metal-organic inclusion complexes that the guest exchange occurs where the guest is the solute molecule. Furthermore, 4 can release the guest, and the original framework was completely recovered after reincorporation of benzene. It should be noted that 4 can incorporate pyrene, phen, and fluorene to give 1, 2, and 3, respectively, after desorption.     

Silver-catalyzed asymmetric Sakurai-Hosomi allylation of ketones

The complex of AgF and (R)-DIFLUORPHOS has been shown to be an effective catalyst for the asymmetric Sakurai-Hosomi allylation of simple ketones. A significaant improvement of the reactivity was observed by using THF as the solvent. The catalyst turnover was increased by addition of 1 equiv of MeOH. AgF and (R)-DIFLUORPHOS predominantly formed a 1:1 complex that provided high enantioselectivity. This catalyst system can be applied to various simple ketones, and corresponding tertiary homoallylic alcohols were obtained with excellent enantioselectivities (up to 96% ee). Only 1,2-adducts were obtained from both acyclic and cyclic conjugate ketones. The regio-, diastereo-, and enantioselective crotylation has also been achieved. E- or Z-crotyltrimethoxysilane gave a similar diastereomer ratio with high enantioselectivities. This finding introduces the utility of racemic allylsilanes for the enantioselective Sakurai-Hosomi allylation reaction.     

Pricing policies under direct vs. indirect channel competition and national vs. store brand competition

This paper analyzes channel pricing in multiple distribution channels under competition between a national brand (NB) and a store brand (SB), where an NB can be distributed both through a direct channel (e-channel) and an indirect channel (local stores) but an SB can be distributed only through an indirect channel. We first explore cross-brand and cross-channel pricing policies. Formulating the problem as a Nash pricing game, we reach two findings: (1) brand loyalty building is profitable for both an NB and an SB; and (2) marketing decisions are more restrictive for an NB channel than they are for the SB channel. We next assess supply chain coordination and reach two findings: (1) wholesale price change does not coordinate the supply chain and (2) an appropriate combination of markup and markdown prices can achieve both supply chain coordination and a win–win outcome for each channel.     

Expansion coefficients and moments of electron momentum densities for singly charged ions

Numerical Hartree–Fock calculations of the first three coefficients of the MacLaurin expansion and the leading coefficient of the large-p asymptotic expansion of the electron momentum densities Π(p) are reported for 54 singly charged atomic cations from He⁺ (atomic number Z = 2) to Cs⁺ (Z = 55) and 43 anions from H⁻ (Z = 1) to I⁻ (Z = 53) in their experimental ground states. We also report all the finite moments <p ^k > (−2≤k≤+4) of the momentum densities Π(p) for the above-mentioned 97 ionic species. The results are compared with the previous ones for neutral atoms [Koga and Thakkar (1996) J Phys B 29: 2973], and the dependence of the expansion coefficients and moments on nuclear charge is discussed among isoelectronic species. Received: 20 November 1998 / Accepted: 15 January 1999 / Published online: 7 June 1999