Cytosine 3-N-Oxide and Its Rearrangement on Acetylation¹

Collisionally activated dissociation of protonated 2′-deoxycytidine, 2′-deoxyuridine, and their oxidatively damaged derivatives

“…Theoretical predictions and experimental data unequivocally support that ring cleavage between the N1 nitrogen and C2 carbon followed by rotation about the C4OC5 bond, ring closure, and proton migration constitute the correct pathway for the rearrangement of adenosine [24,25]. Although there has been no report on the Dimroth rearrangement of unmodified cytosine, dC, or cytidine, the rearrangement of N3-substituted cytosine during acetylation reaction has been observed [26,27]. Moreover, this type of rearrangement has been employed for the syntheses of 15 N3-labeled uridine [28] and cytidine [29] from the 15 N 4 -substituted cytidine N3-oxide.…”

Synthesis of modified pyrimidine bases and positive impact of chemically reactive substituents on their in vitro antiproliferative activity

“…The methylation of 4-thiouracil 23 under the same reaction conditions yielded 4-methylthiouracil 24 [13]. By refluxing 24 with hydroxylamine hydrochloride in dry ethanol followed by treatment with concentrated ammonia, N 4 -hydroxycytosine 25 [14] was obtained (Scheme 4).…”

Novel organic peroxygen reagents for use in organic synthesis

“…3) [14] Baeyer-Villiger oxidation reactions, for example the oxidation ofa 20-ketosteroid which afforded the 17-13-hydroxysteroid after hydrolysis of the ester [13], and the formation of N-oxides as shown in Eq. (4) [15] were also reported as early examples.…”

“…In this way we were able to obtain a high yield of 1,2-epoxyoctane as indicated in Eq. (15). Other examples of the use of these and other procedures are given in Table 1. UHP -Na 2HPO4 (CF3'CO)20, A 0.5 h, 8~8ele "~v'~O (15) The epoxidation of electron deficient alkenes such as methyl methacrylate has also been carried out using reaction conditions similar to those shown m Eq.…”

“…(15). Other examples of the use of these and other procedures are given in Table 1. UHP -Na 2HPO4 (CF3'CO)20, A 0.5 h, 8~8ele "~v'~O (15) The epoxidation of electron deficient alkenes such as methyl methacrylate has also been carried out using reaction conditions similar to those shown m Eq. (15), and with ~,13-unsaturated ketones alkaline hydrogen peroxide has been generated from UHP and affords good yields of epoxides.…”