Lithium aluminum tri-/-butoxyhydride

Lithium aluminum tri-/-butoxyhydride in reduction of 3/3-acetoxy-5-pregnene-20-one, 45, 58... 

The cycloberbine 339 derived from coptisine (65) was reduced with lithium aluminum tri-tert-butoxyhydride to afford the trans-alcohol 340 along with a small amount of the cis-alcohol (Scheme 62). Treatment of 340 with ethyl chloroformate effected C-8—N bond cleavage and simultaneous oxyfunc-tionalization at C-8 with the desired stereochemistry to produce the oxazolidinone 341. This was hydrolyzed with potassium hydroxide and then underwent N-methylation to give ( )-ochrobirine (343). Similarly, the ochrobirine analog 344 was also obtained from berberine (15) (171). 

The 8-methyl-8,14-cycloberbine 364, derived from the protoberberine 324 via the betaine 363, was reduced with sodium borohydride or lithium aluminum tri-tert-butoxyhydride to give a diastereoisomeric mixture of cis-and trans-alcohols (7.8 1 or 1 7.8, respectively) (Scheme 64).t)n exposure to formaldehyde the mixture underwent N-hydroxymethylation and subsequent intramolecular substitution on the aziridine ring to give the oxazolidine 365. Removal of the hydroxyl group in 365 was accomplished by chlorination followed by hydrogenolysis with tributyltin hydride. Reductive opening of the oxazolidine 366 with sodium cyanoborohydride afforded ( )-raddeanamine (360), which has already been converted to ochotensimine (282) by dehydration. 

Lithium aluminum tri-l-butoxyhydride in reduction of 30-acetoxy-S-pregnene-20-one, 46, 58 Lithium amalgam, reaction with 3,4-dichloro-1,2,3,4-tetramethylcy-clobutene, 46, 36... 

Acetoxy-5-pregnene-20-one, reduction by lithium aluminum tri-t-butoxyhydride, 46, 57... 

Lithium tri-f-butoxyaluminum hydride (Lithium aluminum tri-f-butoxyhydride), 1, 620-625 2, 251-252 3, 188. 

Michael addition of methyl vinyl ketone to 24, followed by base-catalyzed cyclization, afforded the j8-diketone 25. Reaction of 25 with phosphorus oxychloride in dimethylformamide gave the vinylogous acid chloride 26 which afforded the corresponding chloro alcohol on reduction with lithium aluminum tri-f-butoxyhydride. Hydrolysis and concomitant dehydration of this chloro alcohol then gave the desired unsaturated ketone (23). 

Reduction of polycyclic quinones. This hydride in DMF is the most efficient of various metal hydrides for reduction of polycyclic quinones to hydroquinones (90 95% yield) with the exception of anthraquinone. With this quinone, lithium aluminum tri-t-butoxyhydride is more efficient (757n yield of the hydroquinone diacetate). ... 

Lass-0 Bleach. See Sodium hypochlorite Lastaron 891. See Sodium polyacrylate LATB. See Lithium aluminum tri-t-butoxyhydride... 

LPG LP gas. See Liquefied petroleum gas LQ-770. See Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate LSP 33. See Tallow dipropylene triamine LT 8049] LT 8052. See Epoxy resin, broniinated LTAC. See Laurtrimonium chloride LTBA. See Lithium aluminum tri-t-butoxyhydride... 

FIGURE 18.25 Lithium aluminum tri- r/-butoxyhydride is not reactive enough to add to the initially formed aldehyde. 

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