Dialdehyde derivatives, preparation

The first total synthesis of D/E-trans annellated yohimbines, e.g., ( )-yohim-bine (74) and ( )-pseudoyohimbine (88), was published in preliminary form by van Tamelen and co-workers (218) in 1958, while full details (219) appeared only in 1969. Key building block 393, prepared from butadiene and p-quinone, was condensed with tryptamine, yielding unsaturated amide 394, which was subsequently transformed to dialdehyde derivative 396. Cyclization of the latter resulted in pseudoyohimbane 397. Final substitution of ring E was achieved via pyrolysis, oxidation, and esterification steps. As a result of the reaction sequence, ( )-pseudoyohimbine was obtained, from which ( )-yohimbine could be prepared via C-3 epimerization. 

Synthesis of a 26jt-electron homologue 81 (1992JA9969) (Scheme 37) has been achieved via the reductive dimerization of dialdehyde 84, prepared from iodopyrrole 82 and an acetylene, employing Sonogashira coupling to obtain 83 after deprotection. For p-methyl-substituted derivatives, a refined procedure has been reported by Kim et al. (1999JOC8048). Similarly 85 obtained from intermediate 83 has been converted into 80. 

The Wittig reaction of dialdehyde 175, prepared by chromic anhydride-pyridine oxidation of diol 94 (53), with 176 in dilute methylene chloride solution produced cyclophane 177 in 86% yield. Epoxidation of 177 with m-chloroperbenzoic acid followed by hydrogenolysis over Pd/C, acetylation, and PtOz-Raney Ni-catalyzed hydrogenation afforded the cis-substituted piperidine derivative (178). 

From similar dilithium derivatives, the dialdehydes were prepared, and through the Wittig reaction polyheteroarylenealkenylenes were obtained. ... 

Dextran-spermine-based conjugates have been prepared via reductive amination between oxidised dextran and spermine [11]. Spermine, a naturally occurring linear polyamine, is involved in cellular metabolism and is a polycation at physiological pH. Dextran was initially oxidised with potassium periodate and the obtained dialdehyde derivative was then reacted under basic conditions with spermine. Dextran-spermine displayed particularly high transfection efficiency, which was attributed to the unique complexation properties between DNA and the grafted spermine moieties. Dextran-spermine and their derivatives have shown high transfection of p-DNA both in vitro and in vivo [12]. 

There are multiple mechanisms of depolymerization, since many of the dialdehyde derivatives are highly susceptible to alkah-catalyzed -elimination, even at moderate temperatures and pH values. Moreover, the degradation of polysaccharide chains caused by free radicals may occur [22, 23]. Periodate itself is unstable and decomposes over time to form radicals, especially in the presence of light. Oxidations are therefore preferentially carried out in the dark and in the absence of oxygen, using freshly prepared periodate solutions. Also, small amounts of trace metals should be removed as they can also catalyse the formation of free radicals. It has been demonstrated that presence of free radical scavenges such as 1-propanol reduces the extent of depolymerization, and it has therefore been routinely added during oxidation, typically at concentrations around 10 % (v/v) [16]. 

The four isomeric 6,7-unsaturated octuronate derivatives 34 (see Vol. 25, Chapter 2, ref. 25 fcM their preparation) have been transformed to the octose noonoacetonides 35 and octitol octaacetates 36, some of which are new compounds. Vanadium (II)-catalysed pinacol cross condensation of the D-xylo-md D-ga/acro-dialdehyde derivatives 37 and 39 with paiafonnaldehyde furnished the d-configurated products 38 and 40, respectively, in a non-chelation controlled process, together with very minor proportions of the corresponding L-sugars."... 

There are four possible classes of bis-5(4H)-oxazolones (cf. 8-11). Compounds of type 8 may be prepared by the Erlenmeyer reaction on dialdehydes. The compound in which R is derived from the 4,4 -dialdehyde of diphenyl ether (R = CgHs) is a recent example. ... 

Since aldehydes are notoriously polymerizable and difficult to manipulate, the products of periodate oxidation are oftentimes further oxidized, with hypohalite, to carboxylic acids, or are reduced to the corresponding alcohols. Oxidation has been more usually employed than reduction, since acids frequently form crystalline salts and other conveniently prepared derivatives. A process of oxidation of these aldehydic products by hypo-bromite, in the presence of barium carbonate or strontium carbonate, was developed and used extensively by Hudson and his coworkers.107 110 194-199,90s Their method can best be illustrated by an example the further oxidation of the dialdehyde, VI, shown previously (see p. 16) to be obtained by the oxidation of the methyl a-D-aldohexopyranosides. The isolation of... 

Reaction of nitromethane and monosaccharide-derived dialdehydes is a useful tool that has been broadly used for the preparation of nitro and amino sugars, and carbocycles.30 Dialdehydes can easily be obtained by oxidative cleavage of conveniently protected monosaccharides with sodium periodate. Their subsequent Henry reaction with a nitroalkene, commonly nitromethane, usually gives isomeric mixtures that require the isolation of the major isomer.31 Thus, treatment of the D-ribose derivative 27 with sodium periodate gave dialdehyde 28, which was subjected to a Henry reaction with nitromethane, to afford nitrosugar 29 as an epimeric mixture (Scheme 11).32... 

Over the last decade, dialdehyde-nitromethane cyclization has established itself as a generally applicable and preparatively satisfactory method for the synthesis of nitrocyclanols, nitrosugars and nitrosugar nucleosides which on hydrogenation are easily converted to the corresponding amino-derivatives... 

A. C. Richardson and H. O. L. Fischer, Cyclization of dialdehydes with nitromethane, Part VI. Preparation of 3- amino-1,6-anhydro-3-deoxy-p-D-gulose, -P-D-altrose and -p-D-idose derivatives and their characterization by means of inversion of mesyloxy groups,./. Am. Chem. Soc., 83 (1961) 1132-1139. 

Encouraged by our previous results, we studied the allylation of bifunctional sulfones derived from dialdehydes such as terephthalaldehyde and isophtha-laldehyde (Scheme 3). When the classical conditions for the preparation of sulfones... 

This technique may also be modified to prepare acetaldehyde derivatives by use of 2,4,4,6-tetramethyl-5,6-dihydro-l,3(4H)-oxazine1 2 3 4 5 6 7 and 2-carboethoxy acetaldehydes using 2-(carbo-ethoxymethyl)-4,4,6-trimethyl-5,6-dihydro-l,3(4H)-oxazine.3 Functionalized aldehydes and dialdehydes may also be obtained by suitable modification.8 Generally, the intermediates can be used without purification and the overall yields of the aldehydes range from 50-70%. 

As with ciimolines, phthalazines were also prepared most frequently through condensations of hydrazine derivatives and carbonyl-containing compounds. For example, Monneret and co-workers reported the condensation of dialdehyde 148 with hydrazine to produce phthalazine derivative 149, an advanced intermediate in the preparation of anticancer analogs of etoposide <99T12805>. 

The first synthesis starting with glutaric dialdehydes and involving intermediates 42 succeeded in preparing unsubstituted 4//-thiopyran (7)19,24 as well as alkylated derivatives.7,90,91... 

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