Imino bonds

Other ureas and thioureas were tested for this reaction. All of the molecules contain an imino bond moiety, which appeared to be beneficial for... 

Pyridine derivatives with additional donor functions and sterically demanding substituents have been used with the intention of producing complexes of Cd (and of other metals) with low coordination number one of these ligands is the tridentate, planar-bonding 2,6-bis[(2,6-dimethyl-phenylimino)methyl] pyridine (pydim a Schiff base derived from 2,6-pyridine dialdehyde), which with Cd(BF4)2 and thiocyanate gives a dinuclear complex [(pydim)Cd(/x-NCS-S,N)]2(BF4)2 with N-dominated coordination sphere.191 As centrosymmetric Plijc, Z= 2), the complex has an antiparallel /x-1,3 NCS double bridge with Cd—N and Cd—S bonds (224.6 pm and 255.5 pm, respectively) the Cd—N(py) bond is clearly shorter than the Cd—N(imino) bonds (225.6 pm and 245.0 pm,... 

Complex (16), which has a similar structure to Co11 salen, catalyzes the electrocarboxylation of arylmethyl chlorides.274 The enhancement of the catalytic life of (16) as compared to Co-salen may be due to the absence of imino bond in its ligand. The catalytic reduction of halogenated compounds has also been attempted at poly[Mn(salen)]-coated electrodes (M = Ni,253 Co275), which might have potential use for determination of organohalide pollutants.275... 

It was suggested that dehydration proceeds almost completely at the GA monomer unit that contains Schiff base imine, but proceeds only little at other GA monomer units. Thus, the formed imino bond is conjugated with the ethylenic double bond, which interaction leading to its stability. 

On-resin reduction of the imino bond of the Boc-Tyr[Bzl(2,6-Cl2)]ip[CH=NNH]Leu-peptide-PAM 48 (300mg, 0.204mmol) was carried out for 12h in a DMF/CH2C12 (1 3) by NaBH3CN following the procedure used for the reductive amination to afford 50. 7 The same procedures for deprotection and cleavage from the resin, as described for the iminoaza peptide, were applied. The yield was estimated at about 45%. Fractions determined to be pure by analytical RP-HPLC are pooled, concentrated under reduced pressure and lyophilized to yield the expected reduced iminoaza peptide 51 (white powder >95% pure) which was checked by TOF-MS calcd, 1255.49 [M + l]+ found, 1255.45. 

Thiirane, imino-bond lengths, 7, 132-133 Thiirane, 2-isopropylidene-3,3-dimethyI-synthesis, 7, 182... 

Interestingly, completely different types of organocatalyst have been found to have catalytic hydrocyanation properties. Among these molecules are chiral diketo-piperazine [4, 5], a bicydic guanidine [6], and imine-containing urea and thiourea derivatives [7-13]. All these molecules contain an imino bond which seems to be beneficial for catalyzing the hydrocyanation process. Chiral N-oxides also promote the cyanosilylation of aldimines, although stoichiometric amounts of the oxides are required [14]. 

One of the few examples of an intramolecular carbene addition to an imino-bond is shown in Scheme 6 <19990L667>. Isoquinoline diazoamide 35 was subjected to standard dirhodium catalysis. The resulting aziridino-isoquinoline 36 was isolated in an excellent 87% yield. The N-O invertomers could be isolated chromatographically. Several other cyclic and acyclic systems were also synthesized. A simple acyclic system provided an 86% yield of a bisazabicyclo[3.1.0]hexane system. A pyrrolizidine aziridine was prepared in 60% overall yield. 

The pyrazolo[l,2-a]pyridazine (55) reacts with sodium methoxide in boiling methanol, presumably via preliminary deprotonation at benzylic carbon. After 8 h a mixture of (56 72%) and the Hofmann-type elimination product (57 12%) is obtained, but after 25 h only (57 75%) is isolated. The imino bond u 1640 cm ) of (57) may be saturated with sodium borohydride. With potassium t-butoxide in t-butyl alcohol at reflux, the rearranged isoindole (58) is obtained (Scheme 22) (74CPB2142). Scheme 23 shows a rearrangement similar to (55) (56) for which a radical mechanism has been suggested. However, here,... 

Schiff bases have been used in electroreductive cyclizations, leading to heterocyclic compounds. The bisimine (24), when reduced in glyme, affords the piperazine (25) in 42% yield after quenching with methyl iodide (equation 10). When the solvent is changed to dimethylformamide, saturation of the imino bonds takes place without ring closure. Transannular ring closure of diazocine (26) led to indolo-... 

This molecule with four coordinated silicon has the shortest Si-N imino bond as far as we know. 

As a rule, simple azavinylogues are unstable compounds, due to the easy hydrolysis of the imino bond. However, the particular case of 0-alkylated oximes (XCHNOY with Y = R or Ar) can be interesting insofar that the oximic imino... 

Reduction of the imino bond results in a decrease but not a loss of activity and ether derivatives retain activity. " Tricyclic oxime (3-blockers showed high selectivity for (32 receptors. " Noxiptyline (Agedal , Bayer) is the oximic equivalent of amitriptyline Review. Hoffmeister " Cry St. Struct Bandoli "). 

Total syntheses of (+)-validamycin B (compoimd 367) [199,200], ( + )-valida-mycin A(365) [201,202], validoxylamine B (362) [200], (+)-validoxylamine A(361) and (+)-validamycin E (compoimd 368) [202] have also been reported by the same group. In another report, cleavage of the imino bonds of validoxylamine A derivatives with A-bromosuccinimide was demonstrated. This method reports the preparation of synthetically useful derivatives of (+)-validamine and valienamine [203]. 

An early synthesis, published in 1983 and 1984 [83], requires three steps from 2-chloro-N-(2,4-dichlorophenyl)acetamide (Scheme 17.17). First, the amide group is transformed into imidoyl chloride with phosphorus pentachloride, followed by displacement of the two non-aromatic chlorine atoms by two equivalents of the potassium salt of 1,2,4-triazole. The triazolyl group borne by the imino bond being the best leaving group is replaced when reacted with a good nucleophile such as (4-chlorophenyl)methanethiol. The stereochemistry (E or Z) of the double bond is not stated in the literature. 

An N-0 bond in oxime derivatives undergoes oxidative addition to form a Pd-imino bond. New Pd-catalyzed reaetions of oximes, such as the amino Heck reaction, have been discovered (see Chapter 3.2.10) [34]. 

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