The Preparation of Catena Compounds by Directed Synthesis

Abstract

Six years ago [2] we discussed some of the principles involved in the synthesis of catena compounds, a new class of substances consisting of rings, which are not chemically combined but which are held together like the links of a chain (I), and began some experimental work on such systems [2,3].As thereactions we envisaged were of s t a t i s t i c a l character, only very poor yields were to be expected. Our experimental results [3] were even more disappointing than expected although they gave valuable information about the behavior and morphology of long-chain and macrocyclic compounds in solution.On the other hand, Wussevmarz [4] claimed to have obtained yields of approximately 1 % (relative to the entire mixture isolated) using one of these methods. Later on he modified this statement to a claim [5] of having obtained by chromatography yields that were several powers of ten less than those previously reported, namely a few milligrams of an oil which was thought to be a catenane. The new principle of the d i r e c t e d synthesis which we have now applied proved successful. By steric control it avoids the extra-annular ring closures which always occur predominantly in statistical cyclization methods. [6] was converted into the dicarboxylic ester (3) by Wittig reaction with an excess of 10-methoxycarbonyldecylidenetriphenylphosphorane [7]. Hydrolysis gave the crystalline dicarboxylic acid (4) (m.p. 67-71 OC, after sintering) in 52 -58 % yield based on (2). Catalytic hydrogenation and esterification of ( 4 ) gave (5). Surprisingly, this ester could not be cyclized by the acyloin ring closure method of Hansley, Pvrlog, and StoN, but remained unchanged, whereas the dicarboxylic ester (6) of a hydroquinone ether was cyclized readily. 4,5-Dimethoxyisophthalaldehyde (2) ____ 0~1 1~The diester (5) was therefore reduced to the diol (7) with LiAIH4, and (7) was converted into the dinitrile (9) via the dibromide (8). The cyclic P-imino nitrile obtained from (

Mechanically Interlocked Molecules (MIMs)—Molecular Shuttles, Switches, and Machines (Nobel Lecture)

“…While Wasserman was carrying out his research at Bell Laboratories in Murray Hill, New Jersey, Gottfried Schill and Arthur Lüttringhaus at the University of Freiburg in Germany were devising ways [17] by which the component parts of a [ 2]catenane could be brought together using acovalent bond that could be cleaved in the final steps of the synthesis.T he key compound shown at the top in Figure 5was obtained crystalline after 14 initially linear steps towards the directed synthesis of the [2]catenane shown at the bottom in Figure 5. Theauthors described the key compound as "one whichislinked intra-annularly and in which the chains of the double ansa-system are situated on opposite sides of the benzener ing.…”

From Chemical Topology to Molecular Machines (Nobel Lecture)

“…One of the first [2]catenanes to be reported in the literature was prepared by Schill and Lüttringhaus more than 50 years ago ( Figure 2). [5] This remarkable piece of work was greeted by the scientific community due to the elegance of the procedure and also due to the impressive synthetic work it represented at the time.U nfortunately,t he complete synthesis required alarge number of steps and, as aconsequence, the overall yield was limited. Despite the novelty of the work, there were very few follow-up contributions from other organic chemists,m ostly because of the extreme difficulty that ag ram-scale synthesis of such compounds would represent following ap urely organic chemistry approach similar to that of Schill and Lüttringhaus.…”

An Introduction to the Mechanical Bond

“…102 Small improvements in the use of this statistical method were made-most notably, Harrison and Harrison's 6% yield of a rotaxane by repeating a statistical threading reaction on a resin-bound macrocycle 70 times, 103 and Zilkha's 104,105 two-step catenane synthesis that converted a statistical [2]rotaxane directly into a [2]catenane in 3% overall yield. Meanwhile, however, Schill was developing an important approach he called directed synthesis, 106 in which macrocycles are built up around an aromatic core such that severing a few bonds at the core in the final steps affords a catenane (Figure 1.9b). This approach was also applied to the directed synthesis of [3] 115 Catenanes, Rotaxanes, and Knots, is an indispensable reference on the early work in the chemistry of mechanical bonds.…”