By Alan R. Katritzky
This quantity within the sequence summarizes the various tools of the synthesis of heterocycles from azadienes with sections masking 1-azadienes, 2-azadienes, and 1,3-diazadienes. It covers the piperazine-2,5-diones and similar lactim ethers - entire evaluate of those hugely vital intermediates for the instruction of a large choice of common items. The ebook explains how 1,2,4-Triazolo [1,5-a] pyrimidines are of specific value in images with different major software in prescription drugs and agrochemicals. It additionally stories tetramic acids, an importantgroup of typical items exhibiting signifcant organic job, in addition to a few chemistry.
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Additional resources for Advances in Heterocyclic Chemistry, Vol. 57
On working in this particular field, we reported the first Diels-Alder reaction of simple neutral 2-azadienes 139 (Scheme 60). Treatment of aliphatic or aromatic aldehydes with substituted 2azadienes 139 at 60°C in the presence of catalytic amounts of boron trifluoride etherate resulted in the stereoselective formation of 1,3-0xazine cycloadducts 271 in 70-95% yield, which arise from an endo transition state (85CB3652). Similarly, cycloadducts 272 and 273 were obtained in 70-90% yield on reaction of 139 with diethyl ketomalonate and butyl glyoxylate, respectively; moreover, hydrolysis and selective exo decarboxylation of 272 led to monoacid 274, whose structure was confirmed by hydrolysis of 273 (89TL2685).
CHzPh R3 = Me. C q M e R5 = Me, Ph, OH, NH2 SCHEME 42 leads to N-trimethylsilyldivinylamines (86CC361). Therefore, one could expect azadienes 139 to participate in [5 + I ] heteroannulations (Schemes 44 and 45). The carbonylation reaction leading to 4(1H)-pyridones 188 was accomplished by room temperature treatment of 139 with N , N ' carbonyldiimidazole in the presence of boron trifluoride etherate [90TL(31)3793;91JOC67511(Scheme 44). In the same way, double nucleophilic displacement on dichlorophosphines allowed the first-time preparation of the 1,4-azaphosphorine ring; stirring at room temperature a mixture of 2-azadiene 139 and dichlorophenyl- or trichlorophosphine in hexane followed by aqueous work-up resulted in the formation of 1,Cdihydro- Sec.
R4 TFA I CH2C12 Me&CONHR1 SiPh2(OMe) N R4 C02Me C02Me 1 2 1 (60-71 96) 122 DMAD : Me@C-CSC-C02Me SCHEME 30 28 [Sec. -DMAD Toluene -20+25"C R4 N / c ~ ~ RM Z = R 3~= H * 117 2 123 'Co2Me 5* DMAD : Me02C-C=Cc-C@Me 125 SCHEME 3I substituted 1,5-diazocine-2(1H)-ones 124, and their aqueous hydrolysis gave quantitatively new 1,2-dihydropyrimidines 125 as well. In the case of starting with azadienes 2 having R2 = R3 = H, the formation of corresponding diazagermocines 123 takes place at -20°C and were not isolated, but either allowed to warm to room temperature to afford 117 or hydrolyzed to pyrimidines 125 (R2 = R3 = H).
Advances in Heterocyclic Chemistry, Vol. 57 by Alan R. Katritzky