Aliphatic Thioketones

Mayer, Roland; Morgenstern, Johannes; Fabian, J.

doi:10.1002/anie.196402771

Cited by 60 publications

(20 citation statements)

References 78 publications

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“…In addition, the rigid structure of 2 which would facilitate stereochemical reasoning, its ready availability in both enantiomeric forms, and the ease with which substituents can be introduced at many positions in stereospecific ways suggested that an investigationof its use as a CDA in glycinate alkylations would prove in~tructive.~ Because of the hindered nature of the carbonyl in 2a, its condensation with amines is known ( 5 ) to be a difficult reaction \ , requiring vigorous reaction conditions. However, prior conversion into the thione 26 (6) markedly increases the facility of "carbonyl" additions (7). For derivatization with glycine esters, the use of 26 appears to be mandatory, as we hatebeen unable to effect such condensations with 2 a under a number of conditions.…”

Section: Introductionmentioning

confidence: 88%

Alkylation of camphor imines of glycinates. Diastereoselectivity as a function of electronic factors in the alkylating agent

McIntosh¹,

Mishra²

1986

Can. J. Chem.

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. J. Chem. 64, 726 (1986).Alkylation of the (R)-camphor imine of tert-butyl glycinate with a variety of alkylating agents gave diastereoselectivities ranging from 0-100%. Simple alkyl halides larger than methyl give de's (diastereomeric excesses) of ca. 50% whereas those derived from allylic type systems afford de's of 75-100%. The results are best explained by invoking a transition state interaction between the 7~ system of the alkylating agent and the imine which, for steric reasons, requires alkylation to occur from the pro-R face. JOHN M. MCINTOSH et PRATIBHA MISHRA. Can. J. Chem. 64, 726 (1986).Les diastCrCosClectivitCs des rkactions d'alkylation de l'imine formCe par la (R)-camphre et le glycinate de tert-butyle par divers agents alkylants varient de 0 h 100%. Les sClectivitCs des reactions affectuCes avec des halogCnures simples plus volumineux que le mCthyle sont de l'ordre de 50% alors que celles effectuCes avec des systhmes de types allyliques vont de 75 h 100%. La meilleure explication de ces rksultats implique une interaction dans 1'Ctat de transition entre le systeme 7~ de I'agent alkylant et l'imine qui, pour des raisons stCriques, nCcessite que l'alkylation se fasse par le face pro-R.[Traduit par la revue] Introduction Some time ago, several reports on the alkylation of chiral imines of glycinates appeared. In particular, the use of menthone (1) and hydroxynopinone (1) (2) gave modest to fair stereoselectivities with the latter being the better chiral derivatizing agent (CDA). The enhanced selectivity using 1 as CDA was attributed to the presence of the extra chelating center, which forced the enolate system into an arrangement in which the steric influence of the syn-methyl group could impede the attack of the electrophile from the top face of the molecule. While more recent developments (3) have displaced this methodology, the rationale given implied that camphor (2a) might be more effective due to the closer proximity of the C-8 methyl group to the carbanionic center. In addition, the rigid

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Section: Introductionmentioning

confidence: 88%

Alkylation of camphor imines of glycinates. Diastereoselectivity as a function of electronic factors in the alkylating agent

McIntosh¹,

Mishra²

1986

Can. J. Chem.

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“…The 2,l-benzisothiazole 3b should be further sulfurized under the conditions of the reaction to 3 -methyl -7'-thioacetyl-2,l-benzisothiazole ( 3 4 , but this is probably readily hydrolyzed back to 3b during the isolation procedure. Certain thiones are reported to undergo such hydrolyses (14). Compounds without substituents capable of interacting with the heterocyclic ring were not sulfurized under the conditions used.…”

Section: S-s-s S-s Smentioning

confidence: 99%

Studies on Some 2,1-Benzisoxazole Derivatives

McKinnon¹,

Wong²

1971

Can. J. Chem.

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(4) indicates that they are in fact best represented by structure l a rather than structures of type lb. Similar considerations also appear to hold for an isothiazole derivative 2a (5) and for a benzo-1,2-thioxole derivative 2b (6). However, it is of interest to examine related compounds in which the central atom is incapable of valency shell expansion to determine to what extent their properties approach those of the 6a-thiathiophthenes 1. These should possibly exhibit valencytautomerism which has been proposed (7) to explain the properties of the thiathiophthenes. A suitable compound for examination is 7-acetyl-3-methyl-2,I-benzisoxazole (3a), which has a structure of the required potential symmetry for n.m.r. examination and possesses similar electronic and structural features to some benzo-1,2-dithiolium derivatives (8) of the thiathiophthene system.2-Nitroisophthaloyl chloride (4a) reacted with ethyl ethoxymagnesiummalonate to provide the tetracarboxylic ester 46. This was not isolated but provided, after acid hydrolysis, 2,6-diacetylnitrobenzene (4c). This method is reported to be the most satisfactory for the preparation of o-nitroacetophenones (9). When the nitro compound was reduced, using stannous chloride in hydrochloric acid, 7-acetyl-3-methyl-2, I-benzisoxazole (3a) and 2,6-diacetylaniline (4d) were S-S-S S-S SR UR R J&AR L R1 = H; R2 = Me; Z = NMe b R1, R2 = CH:C(OMe)-CH:CH; Z = 0 obtained after separation by chromatography. 2,6-Diacetylaniline (4d) was obtained as the sole product when the reaction was performed at a higher temperature.Although the 'H n.m.r. spectrum of the 2,lbenzisoxazole 3a in deuterochloroform solution at 0" to 20" gave only one peak, indicating that Can. J. Chem. Downloaded from www.nrcresearchpress.com by 54.245.55.244 on 05/12/18For personal use only.

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“…[2] Thioketones are more useful and especially the non-enolizable cycloaliphatic representatives are considered as an attractive class of substrates for studies focused on the reactivity of the C=S group. [3] One of the most remarkable features of thioketones is their excellent reactivity as dipolarophiles observed in [3+2] cycloadditions with 1,3-dipoles such as diazoalkanes, [4a] nitrones, [4b,c] thiocarbonyl S-sulfides (thiosulfines), [4d,e] and thioA C H T U N G T R E N N U N G carbonyl ylides. [4e] These cycloadditions open a convenient access to diverse five-membered sulfur heterocycles.…”

Section: Introductionmentioning

confidence: 99%

“…Keywords: alkoxyallenes · desulfurization · thiiranes · thioketones · thiophenes attack, which subsequently undergo a [2,3]-sigmatropic rearrangement, yielding the S-adducts as final products. [8] In recent publications, reactions of 1 a with a series of alkyllithiums were described.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes

Jasiński

Mlostoń

Stolarski

et al. 2014

Chemistry An Asian Journal

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Admantanethione smoothly reacted with lithiated methoxyallene at low temperatures yielding the expected allenyl-substituted thiolate, which upon aqueous work-up underwent spontaneous 1,3-cyclization to afford a hitherto unknown methoxy-substituted vinylthiirane derivative. The analogous reaction with adamantanone led to the corresponding allenyl alcohol that can be isolated and--depending on the conditions applied--either be converted into the corresponding vinyloxirane or into the 2,5-dihydrofuran derivative. Sterically more crowded thioketones were also combined with lithiated methoxyallene, but in these cases competitive 1,5-cyclization leading to isomeric dihydrothiophene derivatives was observed. DFT calculations of model intermediates and products show distinct energy differences of the sulfur and the corresponding oxygen compounds. Desulfurization of the adamantanethione-derived vinylthiirane yielded a methoxy-substituted 1,3-diene that was studied in cycloadditions with electron-deficient dienophiles. Whereas in the case of tetracyanoethylene the corresponding cyclobutane derivative was formed, the reaction with nitrosobenzene provided the expected 1,2-oxazine derivative. By reductive cleavage of the N-O bond this heterocycle was converted into an unsaturated amino alcohol bearing an adamantane moiety.

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Aliphatic Thioketones

Abstract: The methods described in the literature for the synthesis of aliphatic thioketones are examined critically in the light of the authors' own work; new practical methods ofpreparation are reported, and characteristic properties a f thioketones are described.

Cited by 60 publications

References 78 publications

Alkylation of camphor imines of glycinates. Diastereoselectivity as a function of electronic factors in the alkylating agent

Alkylation of camphor imines of glycinates. Diastereoselectivity as a function of electronic factors in the alkylating agent

Studies on Some 2,1-Benzisoxazole Derivatives

Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes

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