Cleavage of nitrates

White GF, JR Snape (1993) Microbial cleavage of nitrate esters defusing the environment. J Gen Microbiol 139 1947-1957. 

Two major pathways are recognized to be of great pharmacological significance in the nonhydrolytic cleavage of nitrates, namely the thiol-dependent pathway and the hemoprotein-dependent pathway. A thiol-dependent pathway is also apparent for organic nitrites [5][30][31]. Before discussing... 

An example of a tandem fragmentation-cyclization reaction is Murphy s tribu-tyltin hydride-induced cleavage of nitrate esters derived from L-(-t-)-tartrate [16a]. The initially formed alkoxyl radical suffers a rapid y9-fragmentation to form a di-oxolanyl radical which undergoes stereoselective cyclization to form a [5,5]-fused dioxolane (Eq. 28). 

Thermal cleavage of nitrate ester 35 (made from L-tartaiic add) produces dioxalanyl radicals which undergo stereoselective cyclizations to lactones 36. ... 

The isomeric 2-deoxy-1,4-lactones 8 and 9 have been synthesized in a multi-step procedure from levoglucosenone, while the branched lactones 10 and 11 have been prepared by radical addition [C6H13I or Ph(CH2)3l, Bu3SnH, AIBN] to an unsaturated aldonic acid ester.The lactone 12, an intermediate in the synthesis of pseurotin A, has been prepared from D-glyceraldehyde in a multi-step procedure. Thermally-induced cleavage of nitrate ester 13 [derived from... 

One example of substituent replacement involves cleavage of a highly branched alkyl group. The alkyl group is expelled as a carbocation, and for this reason, substitution is most common for branched alkyl groups. The nitration of l,4-bis(i-propyl)benzene provides an example ... 

Ceric ammonium nitrate (CAN), CH3CN, H2O, it, 12 h, 96% yield. Benzylamides are not cleaved under these conditions. Some of the methods used to cleave the benzyl group should also be effective for cleavage of the PMB group. Ceric ammonium nitrate is also used to cleave the PMB group from a sulfonamide nitrogen. ... 

Cleavage of the oxathiane moiety can be carried out with iV-chlorosuccinimide/silver nitrate and leads to the a-hydroxy aldehyde 21 along with a diastereomeric mixture of sultines 20. The sultines can be reduced to the hydroxy thiol 22 which can be reconverted to the chiral auxiliary 16 in ail overall recovery of about 70%39. 

In addition to Cyclonite, a nitrate of methylene glycol is also formed as a result of the cleavage of one of the three linkages between each nitrogen and carbon atom 0N02... 

Tracer Studies on the Nitro lysis of Hexamine to RDX and HMX. The formation of RDX and/or HMX molecules from the nitration or nitrolysis of Hexamethylenetetramine (Hexamine) is a complex process and has been postulated to take place via two separate paths. One involves the selective cleavage of the Hexamine molecule to the appropriate cyclic nitramine (RDX, HMX or both) depending on the specific... 

O-acetylophiocarpine (381) with ethyl chloroformate afforded the C-8—N cleaved urethane 382 in quantitative yield. Sequential treatment of 382 with silver nitrate, PCC, sodium hydroxide, and p-toluenesulfonic acid in ethanol furnished acetal 384, which was reduced with lithium aluminum hydride followed by hydrolysis to afford the hemiacetal 385. Oxidation of 385 with PCC provided (+ )-a-hydrastine (369). Similar treatment of O-acetylepi-ophiocarpine (386) afforded ( )-/J-hydrastine (368) however, in this case, C—N bond cleavage of 386 with ethyl chloroformate proceeded without regioselectivity. 

Using day supported ammonium nitrate (dayan), selective deprotection of methoxyphenyl methyl (MPM) ether has been achieved recently using microwave irradiation in solvent-free conditions (Scheme 6.15) [56]. The same reagent has been used for the cleavage of tetrahydropyranyl (THP) ethers. A similar selective preparation and deavage of THP ethers has been achieved under microwave irradiation catalyzed by iodine [57] or neat reaction in an ionic liquid [28],... 

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