Reaction of 1,3-Disubstituted Acetone Derivatives with Pseudohalides: A Simple Approach to Spiro[4.4]nonane-Type Bis-Oxazolidines and -Imidazolidines (Bicyclic Carbamates, Thiocarbamates, Ureas, and Thioureas)

Synthesis of cyclic N‐nitrourethanes by the simultaneous oxidative desulfurization and nitration of cyclic thiourethanes

“…The standard approach to 1 would be nitration of the known 1,6‐dioxa‐3,8‐diazaspiro‐[4.4]nonane‐2,7‐dione [5], 2b , with acetyl nitrate. Compound 2b has been synthesized from the analogous spirodithiourethane, 2a , using basic hydrogen peroxide desulfurization [5] (Scheme 1).…”

“…The yield for the conversion of 2a to 2b is very poor (44%) and the procedure is somewhat lengthy [5].…”

“…This compound was made by the procedure of Köll and coworkers [5]. The melting point (mp) was 205–206°C (ref 5…”

(4R,9S)-4-Hydroxymethyl-3,8-dioxa-1,6-diazaspiro[4.4]nonane-2,7-dithione monohydrate

“…The title compound was prepared in quantitative yield according to the procedure described by Saul et al (2000). The reaction gave a mixture of two diastereoisomers in the ratio 85:15, from which the major compound crystallized in pure form.…”

Thiourea and Selenourea and Their Applications

“…The use of urea instead of thiourea gives 1,3,6,8-tetraazaspiro [4.4]nonane-2,7-dione. This indicates the strong tendency of sulfur to avoid carbon-sulfur double bond in comparison to oxygen thus leading to a much higher nucleophilicity of the sulfur (Scheme 30) [53,54]. 1-Aroyl-3-aryl-4-substituted imidazole-2-thiones have been prepared by the cyclization of 1-aroyl-3-arylthioureas with carbonyl compounds having hydrogen in the presence of bromine and triethylamine (Scheme 29) [52].…”