Three-Membered Ring Heterocycles

2 SYNTHESIS OF VARIOUS HETEROCYCLES 9.2.1 Three-Membered Ring Heterocycles 

Solid-Phase Organic Synthesis Concepts, Strategies, and Applications, First Edition. Edited by Patrick H. Toy and Yulin Lam. 

SOLID-PHASE SYNTHESIS OF HETEROCYCLES FROM PEPTIDES AND AMINO ACIDS 

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Di-TT-methane rearrangements always yield cyclopropane derivatives. Three membered ring heterocycles that could be formed in the ODPM and 1-ADPM processes have never been observed. 

Lewis acid-promoted [3+2] cycloadditions of aziridines and epoxides proceeding via carbon-carbon bond cleavage of three-membered ring heterocycles are demonstrated for the first time. This proposal details plans for extending these initial results into a general synthetic method for the enantioselective synthesis of structurally diverse pyrrolidine- and tetrahydrofuran-containing organic compounds. Expected outcomes of the proposed work will include... 

Selenepines 52a and tellurepines 52b extrude selenium and tellurium, respectively. It is likely that this occurs via formation of the corresponding chalcogenanorcaradiene 53, containing a three-membered ring heterocycle, which rapidly loses chalcogen thermally (Section 1.07.6.2), as shown in Equation (16). Thus 54 cleanly extrudes selenium to form diethyl 4,5-di-/r /t-butyl-phthalate quantitatively, as shown in Equation (17) <1990AGE424>. 

This chapter concerns the net conversion of a C =X ir-bond (X = O and N) to various three-membered ring heterocycles. The most common such process is the conversion of an aldehyde or ketone to a homologous epoxide. These reactions will be discussed along with the analogous process which takes place on imines and related compounds. Additionally, methods to effect the addition of elements other than carbon across either unsaturated system will considered. The synthesis of thiiranes by the addition of carbon across the C—S rr-bond is the subject of a recent comprehensive review and will not be covered here. 

Photochemistry of Three-membered Ring Heterocycles N. R. Bertonniere and G. W. Griffin, Org. Photochem. 105 (1973). 

Ring closure. Di-f-butyldiaziridinone (3), a new three-membered ring heterocycle, has been prepared from 1,3-di-r-butylurea (1) by chlorination (2, f-butyl hypochlorite) followed by ring closure with potassium /-butoxide in /-butanol.2 The overall yield is 90%. The intermediate 1-chlorourea can be isolated, but improved yields are obtained without isolation. Use of potassium metal in pentane lor the cyclization step lowered the yields to 48%. Apparently the two alkyl... 

Dipole from Three-Membered-Ring Heterocycles.258... 

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