3-C-Condensation

Reaction.—a too c.c. flask to a short upright condenser (see Fig. 86) and to the upper end of the condensei attach a vertical delivery tube, dipping into an ammoniacal cuprous chloride solution. Pour 2—3 c.c. of ethylene bromide into the flask with 4 times its volume of strong methyl alcoholic potash, which is prepared by boiling methyl alcohol with excess of caustic potash on the water-bath with upright condenser. On gently heating, a rapid evolution of acetylene occurs and the characteristic brown copper compound (C2H,Cu,HjO) is precipitated from the cuprous chloride solution. 

A mixture of 2.0 grams of 2,3-dihydroxylmino-17a -methyl-5a -androstan-17/3-ol, 5 ml of piperidine and 10 ml of ethylene glycol was heated at a temperature between 180° and 190°C for 30 minutes. After the resulting product was cooled, water was added thereto, and the separated product was filtered, washed with water and dried. The product was dissolved in benzene and passed through a column of alumina. The column was washed with ether, and the eluted fractions were collected and condensed. Subsequently, the residue was recrystallized from ether or aqueous methanol to produce 1.53 grams of 17/3-hy-droxy-17o-methyl-5o-androstano[2,3-C] furazan which has a melting point of 152°C. 

Table 2.2 Energy per 100 kW cooling capacity at 3°C evaporation, 42°C condensation...

Example 33.1 An R.22 direct expansion coil evaporates at 3°C when cooling air from 20°C to 11°C. Condensing is at 35°C. If the air flow is reduced by 15% because of a dirty filter, what is the approximate increase in running cost ... 

Example 35.3 A hermetic compressor is rated at 18.2 kW for R.22 when evaporating at 7°C, suction superheated to 35°C, condensing at 54°C, and with 8 K suhcooling of the liquid. Assuming that the inlet gas picks up another 30 K as it passes over the compressor motor, estimate the change in capacity if the suction is superheated to 12°C. 

More recently, OFETs were made with a dimer of another condensed molecule. dithieno[3,2-/j 2, 3 -c/ lhiophene 100, which presents a very similar structure lo that of benzodithiophene, except that the central benzene ring is changed lo a... 

Diazotization of 4,5-diphenyl-3-amino-l//-pyrazolo[4,3-c]pyridazine gave diazonium salt 290, whose condensation with 2-naphthol gave 291, which cyclized to 292 (91H901) (Scheme 62). 

Thiazolo[2,3-c][l,2,4]triazines 658 were prepared (84LA1302) regio-specifically by cyclizing 2-hydrazono-2-thiazoline 659 with glyoxylic acid or ester. They had herbicidal activity. Condensation of 659 with oxamic acid ethyl ester gave hydrazide 660, which was cyclized with sodium... 

Scheme 10.8 Biosynthesis of epothilone. Individual PKS domains are represented as circles and individual NRPS domains as hexagons. Acyl carrier proteins (ACPs) and thiola-tion domains (T) are posttranslationally modified by a phos-phopantetheinyl group to which the biosynthetic intermediates are covalently bound throughout the chain assembly. The thioesterase domain (TE) cyclizes the fully assembled carbon chain to give the 16-membered lactone. Following dehydration of Cl 2—Cl 3 to give epothilones C and D, the final step in epothilone biosynthesis is the epoxidation of the C12=C13 double bond by the cytochrome P450 enzyme P450epol<. KS ketosyn-thase KS(Y) active-site tyrosine mutant of KS AT acyltransfer-ase C condensation domain A adenylation domain ...

The pyrrolo[2,3-c/]pyrimidine anticancer agent is prepared utilizing, as a key sequence, Michael condensation of 2,6-diamino-4(.37/)-pyrimidinone with nitroalkenes, followed by the Nef reaction that leads to the annulated pyrrole ring (Eq. 10.67).98... 

The [l,3]thiazino[2,3-//]c iiinjzolinone 332 was obtained regioselectively from the 2-(crotylthio)quinazolinone 331 (R = Me) <1996S741>, while 331 (R = Ph) on treatment with excess Bo in AcOH afforded the angularly condensed [ 1,3]thiazino[3,2-z/]quinazolinonc 333 (Scheme 51) <2003CHE640>. 

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