Bimanes. 7. Synthesis and properties of 4,6-bridged syn-1,5-diazabicyclo[3.3.0]octa-3,6-diene-2,8-diones (.mu.-bridged 9,10-dioxabimanes)

Kosower, Edward M.; Pazhenchevsky, Barak; Dodiuk, H.; Ben-Shoshan, Marcia; Kanety, Hanna

doi:10.1021/jo00321a030

Cited by 19 publications

(21 citation statements)

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“…Bromination of the bimane 26 gave a dibromide 29 (92%) that was also converted by treatment with DDQ to syn-(benzo)bimane 28. Treatment with palladium (10%) on charcoal dehydrogenated 5,6,10,-1 1-tetrahydro-7H,9H-benz [6,7]indazol [1,2-a]benz [g]indazol-7,9-dione 35 to syn-(anaphtho)bimane 36 (71%). The bimane 35 was prepared from 1,2,3,4-tetrahydro-1--oxo-2-naphthoate 37 by stepwise treatment with hydrazine to give 1,2,4,5-tetrahydro-3H-benz[g]indazol-3-one 38, followed by chlorine to give 3a-chloro-2,3a,4,5-tetrahydro-3H-benz[g]indazol-3-one 39, and base.…”

Section: L)iimentioning

confidence: 99%

“…Kosower introduced a system of trivial nomenclature for the bimanes based on substitution types. Type I: syn-(A,B)bimanes, Type I: syn-(A,B)(A',B')-bimanes, Type Ill: ji-X-syn-(methylene,methyl)bimanes, Type IV: ani-(A,B)bimanes, and Type V: anti-(A,B)(A',B')bimanes were adopted for this report [6,7]. Laser activity in the spectral region 500-530 nm from syn-(methyl,methyl)bimane 1 was reported in 1986 [5a].…”

Section: L)iimentioning

confidence: 99%

“…Variation in substitution patterns in syn-bimanes has remained limited. In the Kosower scheme for their synthesis chlorination of a pyrazolinone followed by treatment with a base (potassium carbonate or a tertiary amine) brought about the formation of mixtures of syn-and anui-bimanes, eq (1) [6][7][8]. Selected conversions afforded preparative amounts of syn-bimanes with a limited range of substituents.…”

Section: L)iimentioning

confidence: 99%

“…Ring closure between short axis methyl substituents by a one atom bridge afforded p-bridged syn-bimanes [7]. These tricyclic heterocycles were generally obtained from the dibromide 17 in reactions with nucleophiles.…”

Section: Co2c2h5mentioning

confidence: 99%

“…These tricyclic heterocycles were generally obtained from the dibromide 17 in reactions with nucleophiles. We repeated Kosower's preparation of g-(dicarboethoxy)methylene-syn-(methylene, methyl)bimane 5 from the dibromide 17 in a reaction with malonic ester [7], and similarly prepared the homologus dimethyl ester 22. The diester 5 was converted by hydrolysis with decarboxylation to the monocarboxylic acid 23 [7].…”

Section: Co2c2h5mentioning

confidence: 99%

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Bimanes (1,5-Diazabicyclo(3.3.0)Octadiendiones). Laser Activity in syn- Bimanes

Stevens¹,

Boyer²,

Lau³

et al. 1990

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Section: L)iimentioning

confidence: 99%

Section: L)iimentioning

confidence: 99%

Section: L)iimentioning

confidence: 99%

Section: Co2c2h5mentioning

confidence: 99%

Section: Co2c2h5mentioning

confidence: 99%

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Bimanes (1,5-Diazabicyclo(3.3.0)Octadiendiones). Laser Activity in syn- Bimanes

Stevens¹,

Boyer²,

Lau³

et al. 1990

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The Krapcho Dealkoxycarbonylation Reaction of Esters with α‐Electron‐Withdrawing Substituents

Krapcho

Ciganek

2013

Organic Reactions

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The Krapcho reaction involves esters with α‐electron‐withdrawing substituents such as malonates, β‐keto esters, and α‐cyano esters, which undergo dealkoxycarbonylation on being heated in polar aprotic solvents (such as DMSO, DMF, or HMPT) in the presence of water, or in polar aprotic solvents with water in the presence of added salts (such as NaCN, NaCl, LiCl, LiI, or MgCl 2 ). This procedure avoids the use of strongly aqueous acidic and alkaline conditions and tolerates many functional and protecting groups. The chapter presents the mechanistic aspects of this procedure, which include reaction parameters such as solvents, salts, other additives, and the use of microwave irradiation. The diastereoselectivity of protonation of the enolate intermediate leading to the dealkoxycarbonylated products is discussed. Trapping of the intermediate enolate by electrophiles other than a proton is illustrated. Potential side reactions and same‐pot subsequent reactions of substrates are discussed along with functional‐group compatibility for halogens and nitrogen, oxygen, sulfur, selenium, and carbon functional groups. Several examples of applications of this methodology for the synthesis of natural products along with experimental conditions and procedures are presented. Closely related methods are discussed in the Comparison with Other Methods section. The tables, which consist of 371 pages, are grouped according to substrate structure. Selective entries for other methods (excluding classical aqueous acidic or basic methods) are included in the tabular survey for comparative purposes.

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