2- Amino-1,1-diphenyl-1-propanol

During this reaction, two new chiral centres are formed. The formation of one diasteromer with high selectivity shows the potential of the chirality transfer from carbohydrate templates. Conversion of the 2,3-diphenyl alanine into the corresponding 3-amino propanol proved the erythro configuration of the major diaster-eomer. 

When optically active 2-amino-1,1-diphenyl-1-propanol is treated with nitrous acid, there is obtained I,2-diphenyI-l-propanone of inverted configuration but lower optical purity than the starting material. Reaction has taken place with... 

In a series of elegant experiments, Clair Collins (of Oak Ridge National Laboratory) has given us intimate details about the reaction the intermediacy of open carbonium ions, their approximate life-time, and the conformational factors that affect their chemistry. Collins, too, carried out deamination of optically active 2-amino-1,1-diphenyl-1-propanol, but his starting material was labeled stereospecifically (I) with carbon-14 in one of the phenyl groups. He resolved... 

Figure 28.1. Pinacolic deamination of optically active labeled 2-amino-1,1-diphenyl-1-propanol.The most abundant conformer, II, of the dia-zonium ion yields cation 111. Cation III does two things (a) rearranges by back-side migration of Ph, and (b) rotates, in the easiest way possible, to form cation IV, which rearranges by front-side migration of Ph.

Also, amino ketones can be readily converted into amino alcohols by alkali boron hydrides. For example, reduction of 3-amino-1,2-diphenyl-1-propanone hydrochloride by NaBH4 in methanol and subsequent hydrolysis of the boric ester afford pure racemic ery//zr0-3-amino-l,2-diphenyl-l-propanol in 70% yield 392... 

Deamination of amines often gives rise to hot, short-lived carbocations (Section 5.2, p. 226). Deamination of ( + )-1,1-diphenyl-2-amino-l-propanol specifically labeled with 14C in one of the two phenyl groups (25) gives a-phenyl-propiophenone as product, 88 percent of it inverted and 12 percent retained. All the inverted ketone comes from migration of the 14C-labeled phenyl and all the retained from migration of the unlabeled phenyl group (Equation 6.22).39 This... 

In the course of the continuing study [9a,b] on the enantioselective addition of dialkylzincs to aldehydes by using chiral amino alcohols such as diphenyl(l-methyl-2-pyrrolidinyl)methanol (45) (DPMPM) [48] A. A -dibutylnorephedrine 46 (DBNE) [49], and 2-pyrrolidinyl-l-phenyl-1-propanol (47) [50] as chiral catalysts, Soai et al. reacted pyridine-3-carbaldehyde (48) with dialkylzincs using (lS,2/ )-DBNE 46, which gave the corresponding chiral pyridyl alkanols 49 with 74-86% ee (Scheme 9.24) [51]. The reaction with aldehyde 48 proceeded more rapidly (1 h) than that with benzaldehyde (16 h), which indicates that the product (zinc alkoxide of pyridyl alkanol) also catalyzes the reaction to produce itself. This observation led them to search for an asymmetric autocatalysis by using chiral pyridyl alkanol. 

ProMem 28.11 Give the structure of the carbonium ion generated (a) by action of acid on 1,1-diphenyl-1,2-propanediol (b) by action of nitrous acid on l.t-diphenyl-2-amino-1 -propanol. 

Actually the reaction does not appear to proceed by the discrete steps coordination, carbonium ion formation, and rearrangement. Rather, the transformation involves the simultaneous separation of the hydroxyl group (or nitrogen molecule or halogen atom), together with a shift of one of the groups to the backside of the carbon atom from which the separation occurred. Thus the semipinacolic deamination of (+)-l,l-diphenyl-2-amino-l-propanol (XVIII). takes place with a Walden inversion of the carbon atom to which the amino group was attached.16... 

The pinacolic deamination of 2-amino-1,1 -diaryl-1 -propanols provides a convincing case for conformational control. Optically active 2-amino-l,l-diphenyl-l-propanoI 209) affords a-phenylpropiophenone (210) with 88% inversion plus 12% retention (76% inversion plus 24% racemization) at the terminus of phenyl migration 196K The diastereomer (211) of 2-amino-l-anisyl-l-phenyl-l-propanol reacts with preferential... 

A variety of amino alcohols have been examined as modifiers for lithium aluminum hydride. The most effective are 2-dimethylamino-l-phenyl-l-propanol (A-methylephedrine) and ( + )-(2S,3/ )-4-dimethylamino-3-methyl-l,2-diphenyl-2-butanol (Darvon alcohol or Chirald). 

C22H29C0N4OPS2, ((2-((2-(Diethylamino)ethyl)amino)ethyl)diphenyl-phosphine oxide)di-isothiocyanatocobalt(II), 38B, 999 C22H30CUN2O6, Bis(4-formyl-2-methoxyphenolato)(N,N,N, N -tetrameth-ylethylenediamine)copper(II) (red isomer), 44B, 1003 C22H32CUN2O6, Bis(2-amino-2-methy1-1-propanol)copper(II) dibenzoate, 44B, 1003... 

Suitable mechanisms have been proposed following determination of the kinetic and activation parameters for oxidation of 2-naphthol and cyclic ketones by nicotinium dichromate some a-amino acids by tripropylammonium fluorochromate " distyryl ketone by quinaldinium fluorochromate methanol by benzyltriethylammonium chlorochromate catalysed by 1,10-phenanthroline substituted benzyl alcohols by tetraethylammonium bromochromate L-cysteine by pyridinium bromochromate lactic acid and 3,5-dimethyl-2,6-diaryl piperidin-4-one oximes by pyridinium chlorochromate allyl alcohol by IDC benzophenoxime by bispyridine silver(I) dichromate and alkyl phenyl sulfides by cetyltrimethylammonium dichromate. A non-linear Hammett plot obtained for the oxidation of substituted benzyl alcohols by IDC has been attributed to the operation of substituent effect on two steps of the proposed mechanism. " Kinetic and activation parameters for oxidation of o-toluidine and of A-methyl-2,6-diphenyl piperidin-4-one oxime and its 3-alkyl derivatives by sodium dichromate have been determined and suitable mechanisms have been suggested. Micellar catalysis in the 1,10-phenanthroline-promoted chromic acid oxidation of propanol... 

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