ARBONYLS

L-(-)-7-Ami no-a-hydroxybutyric Acid N-hydroxysuccinim ide 6 -Monobenzyloxy[Pg.58]

Synthesis by this route from (-)-(S)-(40) gave (34) ith the same rotation as the original sample. The arbonyl group in (39) was removed by the Wolf-Kishner ethod (table T 24,1). 

C-N disconnection requires difficult (38) so it is t-tter to look for C-C disconnect ions. The strategy of idding an activating group (39) to provide a 1,3-di- arbonyl disconnection is successful (cf p 204)-... 

Aldol condensations are reversible, and with ketones the equilibrium is unfavorable for the ondensation product. To effect condensations of ketones, the product is continuously removed from he basic catalyst. )3-Hydroxycarbonyl compounds are readily dehydrated to give a,j3-unsaturated arbonyl compounds. With Ar on the carbon, only the dehydrated product is isolated. 

B. DIC ARBONYL(fi5-C Y CLOPENT ADIEN YL) (TETR AFLUORO-BORATO) (TRIPHENYLPHOSPHINE)MOLYBDENUM AND TUNGSTEN, MCp(CO)2(PPh3)(FBF3)(M = Mo, W)4... 

E. C ARBONYL(5-THIOXO-l, 3-PENTADIENE-l, 5-DIYL-C1, C S)-BIS(TRIPHENYLPHOSPHINE)OSMIUM, Os(CSCHCHCHCH)(CO)(PPh3)2... 

C. ((I-ACETYL-2KC1 1 k >)-TRIC ARBONYL-1 k2C,2kC-BIS[1 2(i)5-CYCLOPENT ADIEN YL)] (TRIPHENYL-PHOSPHINE-2kP)DIIRON(1 + )... 

Ar Bn Boc Bz Cbz Et /-Bu i-Pr Me n-Bu n-Pr Ph s-Bu f-Bu TBDPS TBS Tf TMS aryl benzyl te rf-butoxy c arbonyl benzoyl benzyloxycarbonyl ethyl isobutyl isopropyl methyl n-butyl n-propyl phenyl sec-butyl ferf-butyl ferf-butyldiphenylsilyl ferf-butyldimethylsilyl trifluoromethanesulfonyl trimethylsilyl... 

Addition of Hydride Donors and of Organometallic Compounds to ( arbonyl Compounds... 

Tris-[2-alkoxycarbonyl-cthyl]- E2, 1 Tris-[2-aminoi.arbonyl-ethyl]- E2,. 1 Tris-[2-biphenylyl]- Xll/1, 136 Tris-[4-biphenylyl]- XII/1, 136, 149, 160 Tris-fchlormcthyl]-... 

The Lewis acid ATPH 97 was effective both in rate enhancement and in control of the regiochemistry i n the cycloaddition reactions b etween C,A-diphenyl nitrone (94) and catalytic amount (10 mol%) of 97, the regiochemistry of the 1,3-DC of 94 and 92 was reversed and the isoxazolidine-4-carbaldehyde 95 was obtained as the major cycloadduct in high yield <02TL657>. 

CoTPP also cleaves dioxetanes such as 2 to dii arbonyl compounds. ... 

Various companies are working on a route to oxidativelyethylene glycol [471 (Equation (22)),... 

Table 18 NickeKO)-catalyzed Intramolecular AllylatiotiAI arbonylation of lodoenynes (284)...

Compounds other than a-haloc arbonyls and thiourea can lead to 2-aminothiazoles. Thus 3-halogenoalkynes (120) condensed with thiourea in absolute alcohol give 2-aminothiazoles (Scheme 56a) (497), with Rj = Me, Et, n-Bu, HjCPh, and H CCgH R-p R2 = H, Ph, C6H4R, and a-naphthyl. Yields ranged from 20 to 80% (497). 

Electrophilic addition to simple alkenes takes place in such a way as to form the most stable intermediate carbonium ion. Addition to a,j3-unsaturatec arbonyl compounds, too, is consistent with this principle to see that this is so, however, we must look at the conjugated system as a whole. As in the case of conjugated dienes (Sec. 8.20), addition to an end of the conjugated system is preferr jd, since this yields (step 1) a resonance-stabilized carbonium ion. Addition to the carbonyl oxygen end would yield carbonium ion 1 addition to the j3-catbon end would yield carbonium ion II. 

The effects of epoxide structure on rates and product distributions indicate that LiC104 reactions occur by a carbenium ion mechanism. Conversely, the LiBr-catalyzed reactions involve bromohydrin salts as precursors to rearrangement products. These are sharp distinctions, and provide the cleanest examples of the two extreme mechanisms for epoxide-[Pg.760]

Addition to prrfluoroolefins and azaolefins. - C arbonyl fluoride reacts with perfluorooldiits to give simple adducts, for example, (6)— ( ). The addition is... 

ZurUmsetzung mit Oxalsaure-diethylestcr zu 2-(Ethoxyc.arbonyl-carbonyl)-l,3-benzothiazol s.Lit.407. 

Triphenyi-phosphor-ylide) 2- (2-Ethoxyc.arbonyl-elhenyl)-l 3-henzot/uazol606 2-(2-Brom-2-methuxycarbonyl-ethenyl,607 2-( 1,3-Benzothiazol-2-yl)-ethenphosphonsdure-diphenylester603... 

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