Pakorn Bovonsombat

Concerning the formations of α-iodoenones

Abstract The formations of α-iodoenones from secondary alkynols with NIS/HTIB (cat.), tertiary alkynols with I 2 /PDC and enones with I 2 /pyridine have been compared. In the latter two reactions the PDC and the pyridine have been found to be catalytic.

Formation of β,β-dihaloenones from halogenated tertiary alkynols

Abstract Halogenated alkynols react with N-halosuccinimides and catalytic amounts of Kosers reagent to afford mixed β,β-dihaloenones, useful templates for aryl and alkyl substituted enones.

Ring expansions of alkynyl cyclopentanols with iodine and Koser's reagent.

Abstract Equimolar amounts of iodine, Kosers reagent, and 1-bromoethynylcyclopentanols with none, one or two methyl groups in the α-position lead to ring expansions in acetonitrile at room temperature in yields of 75 to 85%. In the so-formed 2-[bromoiodomethylidene]cyclohexanones, the (Z) isomer was preferred exclusively in the unsubstituted compound. The Z E ratio was 7.7 for the dimethyl compound and 3.3 for the monomethyl case. The corresponding bromine and Kosers reagent with 1-iodoethynylcyclopentanol afforded a ring expanded product with Z E ratio of 12:1.

Formations of mixed β,β-dihaloenals from halogenated secondary alkynols

Abstract Iodine and Kosers reagent have been used in stoichiometric amounts to convert 3-bromo-1-phenylpropynol to (Z)-3-bromo-3-iodo-2-phenylpropenal in high yield. The latter is a major component of reaction mixtures of 3-iodo-1-phenylpropynol and bromine with Kosers reagent.

Formations of α-Iodoenones by Iodine and Catalytic Amounts of Amines

Abstract Iodine and catalytic amounts of amines in a variety of solvents react with cyclic and acyclic enones to afford the corresponding α-iodoenones.

Ring expansion of an α-bromoalkynol camphor by means of iodine and Koser's reagent

Abstract The bromoethynyl adduct of camphor was treated with equimolar amounts of iodine and Kosers reagent (HTIB) to afford in good yield and in good stereospecificity a (Z)-bromoiodoenone, a synthon for enantiospecific syntheses.

Ring Expansions of 2-Haloethynyl-2-norbornanols

2-Haloethynyl-2-norbornanols react with iodine and Kosers reagent in acetonitrile to afford two ring-expanded products, 2-[(Z)-haloiodomethylidene]bicyclo[3.2.1]octan-3-one and 3-[(Z)-haloiodomethylidene]bicyclo[3.2.1]octan-2-one. These results contrast with the 2-haloethynyl-2-bornanols which lead to the corresponding 3-octanones.

Formation of A Dihaloenone of Homoadamantanone

Abstract Adamantanone is converted to a (Z)-bromoiodomethylidene homoadamantanone via a sequence involving ethynyl Grignard addition, conversion to a bromoalkynol and treatment with iodine and [hydroxy(tosyloxy)iodo]benzene.

A new approach to the functionalization of phenanthrenequinone

Abstract The bromoethynyl adduct of fluorenone was converted to 10-((Z)-bromoiodomethylidene)phenanthren-9-one by means of the iodonium-generating reagent, iodine and Kosers reagent.

Ring halogenations of polyalkylbenzenes by ionic halides and Koser's reagent

Abstract Ring chlorinations of polyalkylbenzenes such as mesitylene have been carried out at room temperature with LiCl or NaCl and stoichiometric amounts of Kosers reagent. Solvents range from water to methylene chloride. The procedures were extended to bromination and iodination.