Heterophilic additions to carbonyls and thiocarbonyls. Scope and stereochemistry

Beak, Peter; Yamamoto, Jiro; Upton, Charles J.

doi:10.1021/jo00909a009

Cited by 67 publications

(18 citation statements)

References 21 publications

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“…In 1974, Rautenstrauch [47] reacted (3-methylbut-2-eny1)lithium with adamantanethiolne and obtained the product resulting from carbophilic attack. One year later, Beak et al [43] reported that the reactions of (benzhydry1)lithium with thiobenzophenone and 4,4'-dimethoxythiobenzophenone, respectively, also proceeded via carbophilic addif ion.…”

Section: Addition Reactions With Organocupratementioning

confidence: 99%

“…The mechanism of direct nucleophilic addition to the thiocarbony1 S-atom was proposed by considering the inverse polarization of the C=S bond [48], or by the HSAB principle [42] [49], as well as by the molecular-orbital theory [50]. This is supported by the reaction of thiocarbonyl compounds with ( Z ) -or @)-substituted prop-2-enyl Grignard reagents, in which retention of the configurafion was observed [43]. For the carbophilic addition of allylic organometallics, even more mechanistic hypotheses were presented, such as reaction through a six-center cyclic intermediate [51-541, via an ate complex 1551 1561, a thiophilic addition followed by a [2,,3]-sigmatropic shift [47], and Scheme 4 10 11 bimolecular electrophilic substitution (&2' mechanism) [57] [58].…”

Section: Addition Reactions With Organocupratementioning

confidence: 99%

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New Addition Reactions of Organometal Compounds with 4,4‐Dimethyl‐1,3‐thiazole‐5(4H)‐thiones

Shi¹,

Heimgartner²

1996

Helvetica Chimica Acta

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Dedicated to Professor H. Suschifzky on the occasion of his 80th birthday (I.XII.95) Addition reactions of organometallic reagents with 4,4-disubstituted 1,3-thiazole-5(4H)-thiones were studied.Whereas the reactions with alkyllithium and alkyl Grignard reagents occurred in the thiophilic manner, the carbophilic addition was observed with allyllithium and ally1 Grignard reagents. A radical reaction mechanism is proposed for rationalizing these observations (Scheme 5). A radical cyclization of the prepared 5-allyl-4,5-dihydro-1,3-thiazole-5-thiol derivatives yielded 1,6-dithia-3-azaspiro[4.4]non-2-enes ( -C=S).In the reactions of 1 with organometallics, it was shown that organolithium reagents undergo thiophilic addition exclusively [ 101. In contrast, organocuprates only afforded products of carbophilic addition [ 111 [ 121. Products of carbophilic and/or thiophilic attack were obtained from the reaction of 1 with Grignard reagents, depending on the nature of the Grignard reagent and the solvent used in the reaction [lo].In this paper, we report on further results from addition reactions of organometallics with a variety of 2-alkyl-substituted 1,3-thiazole-5(4H)-thiones, in which some exceptions of the previously formulated rules were observed, and possible reaction mechanisms are discussed. Furthermore, the radical cyclization of some of the prepared 5-alkenyl-4,5-dihydro-1,3-thiazole-5(4H)-thiioles was studied.

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Section: Addition Reactions With Organocupratementioning

confidence: 99%

Section: Addition Reactions With Organocupratementioning

confidence: 99%

New Addition Reactions of Organometal Compounds with 4,4‐Dimethyl‐1,3‐thiazole‐5(4H)‐thiones

Shi¹,

Heimgartner²

1996

Helvetica Chimica Acta

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“…H) ;7,[6][7]25 (m,3 arom. H);6,[3][4][5]8 (m. CH,); 5,4-5,1 (m, CH,=CH-CH,); 3,l-2,4 (m, mit s bei 2,45, CH,=CH-CH2, SH); 1,92, 1,45 (2s, (CH3),C (4)). "C-NMR: 164,l (7, C(2)); 143,6 (d, CH,=CH-CH,); 133.3, 131,l.…”

Section: Experirnenteller Teilunclassified

“…B. die Umsetzungen mit Phenyllithium (PhLi) ausschliesslich Produkte 2, die durch thiophilen Angriff gebildet werden [ S ] [6]. Demgegenuber verlaufen Reaktionen mit Organomagnesium-Reagen- i + c sn zien je nach Art der Grignard-Verbindung auf drei verschiedenen Wegen [10][11][12] (Schema 1).…”

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“…Intensiv untersucht worden sind Reaktionen von Organometall-Reagenzien und Dithioestern 1 [2] [4] [5] , Dabei liefern z. B. die Umsetzungen mit Phenyllithium (PhLi) ausschliesslich Produkte 2, die durch thiophilen Angriff gebildet werden [ S ] [6]. Demgegenuber verlaufen Reaktionen mit Organomagnesium-Reagen- Bei der Umsetzung von 9a rnit MeMgI in Et,O wurde auch nach 3 Tagen Ruhren bei RT.…”

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Umsetzungen von 1,3‐Thiazol‐5(4H)‐thionen mit Grignard‐ und Organolithium‐Verbindungen: Carbophile und Thiophile Additionen

Jenny

Heimgartner

1986

Helvetica Chimica Acta

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Reactions of I ,3-ThiazoIe-S(4H)-thiones with Crignard-and Organolithium Compounds: Carbophilic and Thiophilic AdditionsOrganolithium compounds and 1,3-thiazole-5(4H)-thiones 9 reacted via thiophilic addition on the exocyclic S-atom. The intermediate anion E has been trapped by protonation to give 12 and by alkylation to yield 16, respectively (Schemes S and 6 ) . In competition with protonation of E, a fragmentation to benzonitrile and a dithioester 14 was observed (Scheme S). In some cases, the alkylation of E led to the formation of dithioacetals 17 instead of 16 (Scheme 6). Methyl, ethyl, and isopropyl Grignard reagents and 9 in THF underwent again a thiophilic addition yielding 4,5-dihydro-l,3-thiazoles of type I2 (Scheme 3). In contrast to this result, MeMgI reacted with 9a in Et20 oiu carbophilic addition to 11. Again a carbophilic attack at C(5) of 9 was observed with allylmagnesium and 2-propynylmagnesium bromide, respectively, in Et20. Einleitung. ~ Thiocarbonyl-Verbindungen haben in der organischen

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Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

1992

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Well over a decade ago, two reviews were contributed to the Organic Reactions series covering substitution and conjugate addition reactions in organocopper chemistry. Their appearance, which highlighted most of the early work in this field, served not only as a source of invaluable references to original literature reports, but also stimulated a vast number of subsequent studies on the properties and uses of organocopper complexes. The work cited in this chapter, which dates from ca. 1975, concerns in large measure uses of organocopper complexes originating from either catalytic or stoichiometric quantities of a copper(I) halide together with a Grignard (RMgX) or organolithium (RLi) reagent. These combinations form either neutral organocopper reagents RCu ( 1 ) or copper(I) monoanionic salts R 2 CuM (M = Li or MgX), commonly referred to as “lower‐order” species. The latter ate complexes with lithium as gegenion ( 2 ) are also known as “Gilman reagents” in recognition of their origins. Copper(I) cyanide is also an excellent precursor, affording homogeneous mixtures of lower order cyanocuprates RCu(CN)Li, ( 3 ), upon treatment with an equivalent of an organolithium. The strength of the CuCN linkage presumably accounts for direct cuprate formation with 1 equivalent of the organolithium, rather than the metathesis that occurs with copper(I) chloride, bromide, or iodide. While use of reagents ( 1 ), ( 2 ) and ( 3 ) alone can be aptly classified as broad‐based and intense, their importance has further encouraged extensive development of variations on these themes (i.e., their composition and reactivity profiles). Reagents ( 1–3 ) have been found to be unexpectedly compatible with certain electrophilic additives at low temperatures, which substantially alter their reactivity. Rather than forming ( 2 ) from 2 equivalents of the same RLi, different organolithiums can be utilized to give R T R R CuLi, ( 4 ), conserving potentially valuable RLi. This scenario raises the question of controlling the selectivity of transfer of the desired ligand R T rather than the anticipated residual (or “dummy”) group R R from copper to electrophilic carbon. Fortunately, many solutions to this problem now exist. Admixture of 2RLi (or R T Li + R R Li) with copper(I) cyanide proceeds beyond the stage of ( 3 ) to ultimately arrive at copper(I) dianionic complexes 5 , the so‐called “higher‐order” cyanocuprates. Undoubtedly it is the cyano ligand, with its π‐acidic nature, which enables copper to accept a third negatively charged ligand. Although reagents ( 5 ) do not yet share in all of the benefits offered by time in comparison with their lower‐order counterparts, they nicely complement prior art. Moreover, as with species ( 1–4 ), they continue to evolve, providing the synthetic community with alternatives for highly selective and efficient means of making key carbon–carbon bonds.

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Heterophilic additions to carbonyls and thiocarbonyls. Scope and stereochemistry

Cited by 67 publications

References 21 publications

New Addition Reactions of Organometal Compounds with 4,4‐Dimethyl‐1,3‐thiazole‐5(4H)‐thiones

New Addition Reactions of Organometal Compounds with 4,4‐Dimethyl‐1,3‐thiazole‐5(4H)‐thiones

Umsetzungen von 1,3‐Thiazol‐5(4H)‐thionen mit Grignard‐ und Organolithium‐Verbindungen: Carbophile und Thiophile Additionen

Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

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