Harold Hart

Iptycenes - Extended triptycenes

Abstract Triptycene is the first member of a large series of compounds for which we have coined the general term “iptycenes”. The prefix (tri, pent, etc.) indicates the number of separated arene planes. By fusing from one to six 9,10-anthradiyl moieties on the triptycene framework, one can derive a first generation of iptycenes (Table 1). Of these, only 3,4,8 and a substituted 2 are known; the remainder provide a synthetic challenge. Potentially interesting practical and theoretical properties of iptycenes and particular structural features of several (i.e. 15,16 and 24) are briefly discussed, as are certain extensions beyond the compounds in Table 1. Methods for preparing useful synthons 35–41 are described. Three new, much improved syntheses of triptycene 29, itself a useful iptycene synthon, are presented. In addition, improved syntheses of pentiptycenes 3 and 33 are described, as well as the first syntheses of pentiptycenes 32,34 and 52 and heptiptycene 54. The way is paved for future development of this mini-domain of unnatural products.

xxx As di-aryxxx equivalents in polycyclic axxx synthesis

Abstract 1,2,4,5-Tetrabromobenzenes and analogous napbthalanes react with one or two equivalents of n -butyllithum and various dienes (furans, pyrroles, cyclopentadienes, fulvenes) to form mono- or bis-cycloadducts. Highly substituted arenes can be obtained by removing the oxygen or nitrogens bridges from the furan or pyrrole adducts. By choice of conditions, two identical or two different rings can be fused to the di-aryne epuivalent. Improved short syntheses of permethylnaphthalene, -anthracene and -naphthacene are described. A new triphenylene synthesis is presented.

Wheel-and-axle design as a source of host-guest compounds. The crystal structure of the 2:1 acetone: tetraphenyl-2,4-hexadiyne-1,6-diol complex

The title diyne-diol crystallizes with an “open” structure containing channels, roughly parallel to the long axis of the host, in which the acetone is hydrogen bonded to the anti-oriented hydroxyl groups.

2′-Substituted meta-terphenyls as building blocks for cyclophanes with intra-annular functionality

Abstract 2′-Substituted m-terphenyls containing chloromethyl and/or thiomethyl groups at the 4,4″ or 3,3″ positions are used as building blocks for cyclophanes with intra-annular functionality. Syntheses are short and yields are good. The methodology, capable of wide structural variation, has been adapted to bi- and tricyclic cyclophanes.

Synthesis and NMR spectra of 3-aryl-1,1,2,2-tetracyanocyclopropanes

Abstract The synthesis of seventeen 3-aryl-1,1,2,2-tetracyanocyclopropanes is described, by a general route. The cyclopropane hydrogen, which appears in the range τ 4·5–5·3 in these compounds, couples with the ortho aromatic protons (J ≅ 0·9 Hz). This is appreciably larger than comparable coupling of the vinyl proton in the corresponding arylidenemalononitriles.

1,3-Bis(1′-Cycloalkenyl)benzenes via a tandem aryne sequence☆

Abstract 1-Cycloalkenyl Grignard reagents react with 2,6-dibromoiodobenzene to give the title compounds. A route to 1,3-bis(cyclopentadienyl)benzene or its synthetic equivalent is also described.

The dilithiation mechanism in the reactions of polyhaloarenes as di-aryne equivalents

Abstract The preparation of certain 1,4-dilithio-tetrahaloarenes is described; they react with electrophiles at low temperatures or form arynes at higher temperatures.

The molecular structure of heptaphenyl-tetraradialene

Abstract It was found by X-ray structural study that the title radialene is puckered and its seven phenyl groups are not arranged regularly.

Vinylsilyl Grignard reagents as aryne traps. A new route to (arylalkenyl)silanes.

Abstract A general method for preparing (arylalkenyl)silanes via nucleophilic capture of arynes with vinyltrimethylsilyl Grignard reagents is described.

N,N'-DITRITYLUREA AND ANALOGS AS HOSTS IN CRYSTALLINE CLATHRATE COMPLEXES : SYNTHESIS AND SELECTIVITY STUDIES

Abstract Of 38 hosts, most of them new, designed on the ‘wheel-and-axle’ model, 24 formed clathrate complexes with small molecules; 95 new host/guest combinations are described (Table 6). Selectivity studies (Table 7) show, in some instances, substantial discrimination between guests with similar structures.