Conversions into dialdehydes

The traditional approach to this ring system involves adding hydrazine to [1,2,3]triazole, 5-dialdehyde to condense the fused pyridazine ring <1996CHEC-II(7)489>. Eor example, Trudell and co-workers reported the conversion of dialdehyde 63 into the fused pyridazine ring compound 64 by reaction with hydrazine monohydrate at 50 °C (Scheme 44) <2000JHC1597>. 

Addition of 4-pentenyllithium to the dione 65 gave the ds-diol 71 which was converted to the (Z)-l,2-disubstituted cyclododecene 72a. Hydroboration-oxidation and chromium trioxide oxidation provided the dialdehyde 72b whose McMurry ring closure, followed by partial catalytic hydrogenation gave the (Z)[10.10] precursor 73. Treatment of this (Z)-olefin 73 with HzS04-Ac0H in benzene was reported to effect conversion into [10.10]betweenanene (61b) of 95% purity and high yield. 

There is abundant information to support the contention that the lower-melting monoisopropylidene-mannitol (m. p. 85°) is the 3,4-derivative. For example, its tetrabenzoate is identical with that obtained by acetonation of 1,2,5,6-tetrabenzoyl-mannitol,11498 the structure of which is based on independent evidence.114 The larger fragment resulting from the oxidative scission of the D-enantiomorph of the isopropylidene-man-nitol with lead tetraacetate is 2,3-isopropylidene-D-//treo-dihydroxy-succinic dialdehyde, characterized by its subsequent conversion into D-i/ireo-tartaric acid.126 When methylated and hydrolyzed, the L-enantio-morph of the monoketal affords a tetramethyl-mannitol, which, in turn, yields dimethyl-L-glyceraldehyde with lead tetraacetate.127 Each of these facts is in itself proof that the acetone residue occupies the 3,4-position in the mannitol molecule. 

Cookson R, Lane RM (1976) Conversion of dialdehydes into cyclic a-ketols by thiazolium salts synthesis of cyclic 2-hydroxy-2-enones. J Chem Soc Chem Commun 1976 804... 

Fig. 15 (a) Formation of a polymer (53 or 55) on reaction of a pyridine-hydrazone-pyridine derived dialdehyde 50 with 1 equiv. of diamine (51 or 52), and its reversible conversion into a macrocycle (54 or 56) in the presence of the appropriate metal ions (b) stylized representation of the polymer/macrocycle reversible switch... 

In connection with preliminary structural work on the hexitols, an unexpected result arose during attempted identification, by conversion into a (p-nitrophenyl)hydrazone, of the dialdehydes (8) or (9), formed by periodic acid oxidation of tbe anhydrodeoxyhexitols (6) and (7), or (21) and (22). The dialdehydes (8) were cleaved to form glyoxal and a 2-deoxytetrose [isolated as the (p-nitrophenyl)hydra-zone ]. 

In the oxidation of indene [39] and of 1,2-diphenylcyclobutene [25] with singlet oxygen generated by irradiation of the solutions of the compounds in the presence of sensitizers, dioxetanes are the probable intermediates in the conversion of the unsaturated hydrocarbons into dialdehydes and diketones, respectively. Different products may be formed depending on the solvents used (equation 65) [25]. 

An initial cyclization to the oxazoline (159) is involved in the photodecomposition of propyzamide (160), and the conversion of dialdehyde (161) into ( )-cw-alpinigenine (162) is the result of photoinduced enolization followed by thermal [ 4 -I- 2] cycloaddition. 

These reagents have been used for the conversion of Q symmetrical chains into chiral non-racemic products. Condensation of mcio-dialdehydes with Cp(/ ,/ )-Ti[All] or Cp(5,5)-Ti[All] reagents led (after reduction with NaBH4) to optically active polyketides (eq 12). ... 

Piperidine acetate also catalyzes the intramolecular cyclization of dialdehydes. Examples cyclization of (1) to (2) by Woodward et al conversion of (3) into... 

The second furan derivative which can be prepared from the appropriate C6 polysaccharides or sugars is hydroxymethylfuraldehyde (HMF). The mechanism of its formation from hexoses is entirely similar to that of F, but difficulties associated with the recovery of the product have delayed its industrial production, despite, again, the ubiquitous character of its natural precursors. A very substantial effort has been devoted in recent years to investigate and optimize novel processes and/or catalysts [36] and the ensuing results suggest that HMF will be a commercial commodity very soon. Interestingly, because of its relative fragility, some of these approaches consider the in situ conversion of HMF into its very stable dialdehyde (FCDA) or diacid (FDCA) derivatives. 

Various cyclitols (and acyclic polyols) have been desynunetrized by formation of dispoke intermediates. (See for example, Vol. 28, p. 237, ref. 115). L-Chiro-inositol can be converted to the silyl derivative 67 in which the trans-diol units are protected on reaction with l,3-dichloro-l,l,3,3-tetraisopropylidisiloxane (TipsQ). Compound 67 was further converted into conduritol B epoxide and its thioepoxide analogue. The conversion of some tetra-O-substituted myo-inosi-tols into adipic dialdehyde derivatives is mentioned in Chapter IS. 

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