Practical Method for Preparation of (S)-2-Amino-5,5,5-trifluoropentanoic Acid via Dynamic Kinetic Resolution

This work reports an operationally convenient ∼20 g scale synthesis of (S)-2-amino-5,5,5-trifluoropentanoic acid and its Fmoc-derivative via dynamic kinetic resolution of the corresponding racemate.

Discovery and structure-activity relationship of imidazolinylindole derivatives as kallikrein 7 inhibitors

A series of imidazolinylindole derivatives were discovered as novel kallikrein 7 (KLK7, stratum corneum chymotryptic enzyme) inhibitors. Structure-activity relationship (SAR) studies led to the identification of potent human KLK7 inhibitors. By further modification of the benzenesulfonyl moiety to overcome species differences in inhibitory activity, potent inhibitors against both human and mouse KLK7 were identified. Furthermore, the complex structure of 25 with mouse KLK7 could explain the SAR and the cause of the species differences in inhibitory activity.

Novel regiocontrolled protection of 1,2- and 1,3-diols via mild cleavage of methylene acetals

The regiocontrolled protection of unsymmetrical 1,2- and 1,3-diols has been developed. Different types of protected diols are available from the methylene acetal in a one-pot procedure. Highly regioselective protection of diols with a silyl group at the less hindered hydroxy group as well as with a MOM group at the more hindered one were achieved. The reaction conditions are mild without affecting other functional groups including acid-labile function.

Organoiodine-Catalyzed Oxidative Spirocyclization of Phenols using Peracetic Acid as a Green and Economic Terminal Oxidant

The use of peracetic acid as a green and economical terminal oxidant in fluoroalcohol solvents could provide a practical iodoarene-catalyzed oxidation of phenols to give spirodienones. Acetic acid and water were the only co-products and waste, and thus this catalytic approach utilizing fluoroalcohol media could simplify the reaction workup procedure for product isolation.

A new H2O2/acid anhydride system for the iodoarene-catalyzed C-C bond-forming reactions of phenols

We have succeeded in the first versatile iodoarene-catalyzed C-C bond-forming reactions by development of a new reoxidation system at low temperatures using stoichiometric bis(trifluoroacetyl) peroxide A in 2,2,2-trifluoroethanol (TFE). The catalytic system supplies a wide range of substrates and functional availabilities sufficient to be used in the key synthetic process of producing biologically important Amaryllidaceae alkaloids.

Versatile direct dehydrative approach for diaryliodonium(III) salts in fluoroalcohol media

We have found that the use of fluoroalcohol media greatly enhanced the efficiency and scope of the direct dehydrative condensation of arenes and hypervalent iodine(III) compounds; the present clean method has a broad range of applicability as well as unique selectivity in the aromatic substrates, and is highly efficient even in polymer functionalization.

First hypervalent iodine(iii)-catalyzed C–N bond forming reaction: catalytic spirocyclization of amides to N-fused spirolactams

A protic solvent, 2,2,2-trifluoroethanol (CF(3)CH(2)OH), was successfully introduced into hypervalent iodine(III)-involved catalytic cycles as an effective solvent, and the first iodoarene-catalyzed intramolecular carbon-nitrogen bond forming reaction was achieved under strong acid-free and mild conditions.

Successful treatment of a patient with lymphomatoid papulosis by methotrexate

We report a case of lymphomatoid papulosis (LyP) that occurred in a 44-year-old Japanese male patient. Reddish papules with a small number of pustules and nodules were observed on the extremities, chest and upper back. Most lesions were also associated with central necrosis, ulceration and crusting, and regressed spontaneously within 4 to 6 weeks. Histopathological examination revealed wedge-shaped dense cellular infiltrate in the dermis, which was mixed with large atypical lymphoid cells, small lymphocytes, eosinophils and neutrophils. These large atypical cells expressed CD30 on their cell membrane and cytoplasm. Rearrangement of the T-cell receptor (TcR) beta-chain gene was detected in the skin lesion. Lymphadenopathy with histopathologic change similar to the skin lesions, but without TcR gene rearrangement, was found at the left inguinal area. Systemic administration of methotrexate (7.5-15.0 mg/week) was found to be dramatically effective in resolution of skin lesions and prevention of their recurrence.

Sulfur containing tyrosine analogs can cause selective melanocytotoxicity involving tyrosinase-mediated apoptosis

Sulfur-containing tyrosine analogs such as 4-S-cysteaminylphenol (4-S-CAP) and its N-acetyl derivative, N-acetyl-4-S-CAP, are tyrosinase substrates and can cause selective cytotoxicity or cell death of melanocytes and melanoma cells. It is not clear, however, if the cytotoxicity derives from a cytostatic or cytocidal effect. The latter can also be either apoptotic or necrotic. This paper summarizes our attempt to clarify the nature of melanocytotoxicity and cell death by using a new derivative of 4-S-CAP, N-propionyl-4-S-CAP (NPr-CAP). The i.p. administration of NPr-CAP caused marked depigmentation of black hair follicles in C57 mice. At 12 h postadministration of NPr-CAP, follicular melanocytes showed histochemical and morphologic features indicative of apoptosis by TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining and electron microscopy. The agarose gel electrophoresis of DNA from drug-treated melan a2 cells, an immortal melanocyte line of C57 black mice, showed the nucleosomal DNA ladder pattern. NPr-CAP caused irreversible cytotoxicity in melan a2 and the effect was inhibited by a tyrosinase inhibitor, phenylthiocarbamide. The tyrosinase-mediated cytotoxicity of NPr-CAP was further confirmed by the decreased viability of COS 7 monkey-kidney cells, which expressed a level of high tyrosinase activity through transfection of human tyrosinase cDNA. NPr-CAP, however, also transiently inhibited the proliferation of melan c cells, a control tyrosinase-negative albino melanocyte line, and vector-transfected COS 7 cells. Thus, the major process of NPr-CAP-mediated melanocytotoxicity involves cytocidal apoptosis associated with active tyrosinase. In addition, there is transient, nontyrosinase-mediated cytostatic cytotoxicity.