Peterson condensation

Tylonolide hemiacetal (33), the aglycone of the antibiotic tylosin, possesses an anti 14-hydroxymethyl-15-acyloxy stereochemistry conveniently contained in 26, which may be viewed as the western half of 33. In order to prepare the eastern half of 33, an aldol reaction leading to the desired syn stereochemistry at C-3 and C-4 is exploited. The reaction of achiral aldehyde 27 with the S-boron enolate 28 proceeds with the expected diastereofacial selectivity to provide, in a combined yield of 80% after O-silylation, a separable mixture of 29 (derived from the / -enantiomer of 27) and 30 (from the S-enantiomer of 27). Subsequent functional group transformation of 30 ultimately leads to the a-(TMS)methylketone 31. The anion of 31, generated with lithium hexamethylsilazide in THF at — 78 °C, undergoes a Peterson condensation with 26 to afford in 60% yield the seco-diC d 32. Treatment of 32 with 70% acetic acid at 85 °C for one hour affords 33 in 60% yield. The attractive feature of this... 

Michael-Peterson Condensation. 3-Trimethylsilyl-3-buten-2-one also undergoes smooth Michael addition with Grignard reagents (R = Me, n-Pr, i-Pr, f-Bu, Ph), generating magnesium enolates which are then trapped with benzaldehyde to give ( )-and (Z)-enone isomers after Peterson condensation (eq 6). For example, treatment of the a-silyl vinyl ketone with methylmagne-sium iodide followed by reaction with benzaldehyde yields a 7 1... 

Carey VP (1992) Liquid-vapour phase-change phenomena. Hemisphere, Washington, DC Collier SP (1981) Convective boiling and condensation. McGraw-Hill, New York Ha JM, Peterson GP (1998) Capillary performance of evaporation flow in micro grooves an analytical approach for very small tilt angles. ASME J Heat Transfer 120 452 57 Hetsroni G, Yarin LP, Pogrebnyak E (2004) Onset of flow instability in a heated capillary tube. Int J Multiphase Flow 30 1424-1449... 

The condensation of aldehydes and ketones with aminoacetonitriles, although it requires more vigorous soliddiquid catalytic conditions to produce the cyano-enamines, is preferable in many respects to the traditional Wittig-Horner or Peterson procedures [45]. Hydroxyalkylphosphonates are obtained from the catalysed aldol condensation of nitromethane with acylphosphonates [46]. 

Magnesium, 235 Samarium(II) iodide, 270 Titanium(IV) chloride, 304 Addition reactions to carbonyl groups—Addition of functionalized CARBON NUCLEOPHILES (see also Aldol reaction and other specific condensation reactions, Meth-ylenation, Peterson Olefination, Refor-matsky reaction, Wittig reaction, Wittig-Horner reaction)... 

Figure 3.5. Schematic arrangement of the various phases of behenic acid (docosanoic acid) at the air/water interface corresponding to the phase diagram shown in Figure 3.6. (Taken from Kenn, R.M., Bohm, C., Bibo, A.M., Peterson, I.R., MOhwald, H., Als-Nielsen, J. and Kjaer, K. 1991 J. Phys. Chem. 95 2092-7. Published by permission of the American Chemical Society and the authors.) All the phase structures are distorted forms of hexagonal packing. denotes an end view of a molecule which stands vertically but does not rotate about its axis and is in the phase denoted by CS. is similar to the above but is in the S phase and librates. O denotes a molecule the axis of which is vertical and which rotates about its axis. denotes a tilted molecule. In the liquid expanded, L2, phase the tilt is towards the nearest neighbour and in the liquid condensed, L, phase the tilt is towards the next nearest neighbour.

Peterson olefination of the aldehyde 171b with l-trimethylsilylprop-3-ynyl lithium 137), furnished a (Z, E) mixture of enynes 225 in 85 % yield. Desilylation with KF in DMF l38), metalation with n-butyllithium, condensation with hexanal and lithium aluminum hydride reduction gave the conjugated dienol 226 in 72% overall yield from 171b. Treatment of 226 with 10 mol. % of PPTS 1011 in ethanol at 55 °C led directly, within 30 min, as monitored by t.l.c. to (E, E)-2-( 1,3-nonadienyl)-cyclo-butanone 227 (Eq. (70))96). This C3 -> C4 ring enlargement occurred under rather mildly acidic conditions since the pH of a 1 M aqueous solution of PPTS is 3.0 101 K... 

Synthesis and Reaction Chemistry of a,p-Unsaturated Acyl Complexes Derived from (2). Two methods for the preparation of optically active ( )- and (Z)-a,p-unsaturated iron acyls from (2) have been reported." One method involves aldol condensation of (2) with aldehydes followed by 0-methylation to produce diastereomeric acyls (18). This mixture (18) is then treated with Sodium Hydride to produce predominantly ( )-a,p-unsaturated acyl complexes (19) (eq 13). Alternatively, (2) can be depro-tonated and treated with Chlorotrimethylsilane to produce the C-silylated complex which is subsequently deprotonated and treated with an aldehyde. This Peterson alkenation produced mixtures... 

A, Condensation using diisopropylethylamine B, metal-chelate C, ammonium salt of acetic anhydride D, acetic anhydride condensation E, Peterson olefination F, condensation G, (CF3)2C=C=0 plus di-p-tolylcyclopropenone. 

The use of cerium trichloride for the Peterson alkenation has been q)plied by Ueda and cowoikers for nucleoside synthesis (Scheme S2). The anion was generated with LDA/cerium trichloride and condensed with the aldehyde (375). The product was treated with KH in THF and the pyrimidopyridine (377) isolated in S0% yield. 

In the P-ketosilane approach, the condensation of a-silyl carbanions with carbonyl compounds produces mixtures of diastereomeric P-hydroxysilanes. Therefore, the preparation of stereodefined alkenes via the Peterson reaction hinges on the availability of just one diastereomer. To overcome this shortcoming, procedures have been developed to prepare stereoselectively P-hydroxyalkylsilanes via the P-ketosilane or the epoxysilane routes, as exemplilRed below. 

Table 13.4 compares the properties of coagulation and condensation with respect to the total number of particles and the total particle volume. Coagulation reduces particle number but the total volume remains constant. Condensation, since it involves gas-to-particle conversion, increases total particle volume, but the total number of particles remains constant. If both processes are occurring simultaneously, total particle number decreases and total particle volume increases. A detailed study of the interplay between coagulation and condensation has been presented by Ramabhadran et al. (1976) and Peterson et al. (1978) to which we refer the interested reader. 

Peterson, T. W., Gelbard, F., and Seinfeld, J. H. (1978) Dynamics of source-reinforced, coagulating, and condensing aerosols, J. Colloid Interface Sci. 63, 426-445. 

Aldol reaction and other specific condensation reaciKMu, Meth> Venation, Peterson Olcfination. Rcfoi-matsky reaction. Wtttig reacbon, Witrig Homer teaetkm)... 

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