Toshio Hasegawa

SYNTHESES OF CYCLOHEPTATRIENES WITH SULFUR FUNCTIONAL GROUPS

Abstract Disodium 1, 6-disulfido-1, 3, 5-cycloheptatriene 3, formed by reduction of 1 with sodium in liq. ammonia, reacts with hydrogen chloride and methyl iodide to give 1, 6-dimercapto-, 4, and 1, 6-bis(methylthio)-1, 3, 5-cycloheptatrienes 5 respectively; however, it is oxidized by bromine to afford cyclic disulfide 6. 1, 6-Diiodo-1, 3, 5-cycloheptatriene 2 is converted to 1, 6-bis(benzylthio)-1, 3, 5-cycloheptatriene 7 by reaction with sodium phenylmethanethiolate, whereas similar reactions with 1-(2-hydroxyethyl)-6-iodo-1, 3, 5-cycloheptatriene 9, obtained from 2 via 1-iodo-6-vinyl-1, 3, 5-cycloheptatriene 8, give 1-benzylthio-6-(2-hydroxyethyl)-1, 3, 5-cycloheptatriene 10. 1-Benzylthio-6-benzylthioethyl-1, 3, 5-cycloheptatriene 11 is synthesized by the reaction from 9 via 1-(2-bromoethyl)-6-iodo-1, 3, 5-cycloheptatriene 10. Attempts to synthesize thiols from 7, 11, and 12 are also described.

Experimental and Theoretical Analyses of Azulene Synthesis from Tropones and Active Methylene Compounds: Reaction of 2-Methoxytropone and Malononitrile

A representative azulene formation from an active troponoid precursor (2-methoxytropone) and an active methylene compound (malononitrile) has been analyzed both experimentally and theoretically. (2)H-Tracer experiments using 2-methoxy[3,5,7-(2)H(3)]tropone (2-d(3)) and malononitrile anion give 2-amino-1,3-dicyano[4,6,8-(2)H(3)]azulene (1-d(3)) in quantitative yield. New and stable (2)H-incorporated reaction intermediates have been isolated, and main intermediates have been detected by careful low-temperature NMR measurements. The detection has been guided by mechanistic considerations and B3LYP/6-31(+)G(d) calculations. The facile and quantitative one-pot formation of azulene 1 has been found to consist of a number of consecutive elementary processes: (a) The troponoid substrate, 2-methoxytropone (2), is subject to a nucleophilic substitution by the attack of malononitrile anion (HC(CN)(2)(-)) to form a Meisenheimer-type complex 3, which is rapidly converted to 2-troponylmalononitrile anion (5). (b) The anion 5 is converted to an isolable intermediate, 2-imino-2H-cyclohepta[b]furan-3-carbonitrile (6), by the first ring closure in the reaction. (c) A nucleophilic addition of the second HC(CN)(2)(-) toward the imine 6 at the C-8a position produces the second Meisenheimer-type adduct 7. (d) The second ring closure leads to 1-carbamoyl-1,3-dicyano-2-imino-2,3-dihydroazulene (11). A base attacks the imine 11, which results in generation of a conjugate base 12 of the final product, azulene 1.

Dynamic Fracture and Fragmentation of Ice Materials

By simultaneously operating high-speed digital video cameras, we have been experimentally investigating the mechanical characteristics of ice spheres that impinge upon a fixed elastic plate consisting of ice/polycarbonate. We have found that, when ruptured under dynamic impact, ice spheres show two specific fracture patterns: “top” and “orange segments.” Our three-dimensional finite difference calculations simulating impact on linear elastic spheres indicate that “top” (“orange segments”) fracture pattern is generated due to a shorter (longer) contact time during the impact process, respectively. Here, using pressure sensors, we try to clarify more quantitatively the generation mechanism of two dynamic fracture patterns. The new experimental observations suggest that the rise time (the time needed to reach a certain pressure owing to impact) is basically shorter when the generated fracture is the “orange segments”-type. This shorter rise time renders a longer effective contact time and hence waves of longer lengths, consistent with our earlier speculations.

Dr. Howard C. Taylor—Developer of friendship and amity

THE DEDICATION of a Festschrift to Dr. Howard C. Taylor, Jr., by the Publisher and Editors of the AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY is indeed a heartwarming undertaking. It is a well deserved honor in which I am pleased to participate. Dr. Taylor, Editor Emeritus of the JOURNAL, ‘Professor Emeritus of Obstetrics and Gynecology, Cohunbia University, and Director, International Institute for the Study of Human Reproduction, has and is providing meritorious service to the JOURNAL, to obstetrics and gynecology, and in the forming of international relationships. In 1950, only five years following the end of World War II, Dr. Taylor provided me the opportunity to present a paper at the International and Fourth American Congress of Obstetrics and Gynecology. In 1954 he, as Editor of the JOURNAL, asked that I contribute an article to the Festschrift for