I Aldehyde

These results support a mode of ring closure shown in Fig. 5. So far, it has not been possible to synthesize the proposed intermediate isochanoclavine I aldehyde. Chanoclavine I aldehyde is converted to chanoclavine I in cultures of Claviceps, but the conversion of chanoclavine I to chanoclavine I aldehyde could not be demonstrated because chanoclavine I aldehyde could not be recovered from the cultures (Floss et aL, 1974a). Nevertheless, the evidence strongly suggests that chanoclavine I aldehyde is an intermediate between chanoclavine I and the clavine alkaloids. 

To test this mechanism, a 1 1 mixture of [2- C]mevalonate (86% C) and [4- H2]mevalonate was fed to Claviceps strain SD 58, and the mass spectra of chanoclavine I and elymoclavine were analyzed for the percentage excess of M -I- 1 and M + 2 species (Floss et ai, 1974a). Chanoclavine I contained only M + 1 (monodeuterio or C) species. However, elymoclavine contained 7% M + 2 species because of intermolecular transfer of deuterium from [9- H]chanoclavine I to a [ C]chanoclavine I molecule. NMR analysis of elymoclavine biosynthesized from [4- H2]mevalonate showed that all the deuterium was located at C(9), establishing that the hydrogen is transferred back to the 9 position. 

When (4R)-[2- C,4- H]mevalonate was fed to Claviceps cultures (Floss et ai, 1974a Tabacik et al., unpublished results), tritium retention was 

A mechanism incorporating the formation of chanoclavine I aldehyde and the intermolecular transfer of the hydrogen at C(9) is shown in Fig. 7. The carbinolamine is the product in path a, and isochanoclavine I aldehyde 

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KETONES ft I aldehydes 2740 3UCj J JtSO-kfiO 1 [vdoo) 1-420 fc-ri 6 -CKi-CO 1 ... 

The hydroformylation of olefins discovered by Otto Roelen [ 151 ] is one of the most important industrial homogeneously catalyzed reactions [152,153] for the synthesis of aldehydes with an estimated production of more than 9.2 million t in 1998 [ 153]. Hydroformylation is the addition of hydrogen and carbon monoxide to a C,C double bond. Industrial processes are based on cobalt or rhodiiun catalysts according to Eq. 1. The desired products are linear (n-) and branched (i-) aldehydes, in which the hnear products are generally favored for subsequent processing. 

Oxidation of the d-(-i-(-aldehyde does not affect any of the bonds to the chiral C. The acid has the same d configuration even though the sign of rotation is changed. 

CARBONYL COMPOUNDS I. ALDEHYDES AND KETONES. ADDITION REACTIONS OF THE CARBONYL GROUP... 

Carbonyl Compounds I. Aldehydes and Ketones. Addition Reactions of the Carbonyl Group halides). The naming of these compounds is described in Sections 7-4 to 7-7. 

Carbonyl Compounds I. Aldehydes and Ketones. Addition Reactions of the Carbonyl Group... 

These catalyst systems were discovered and studied first by G. Wilkinson and co-workers in the 1960s (3). Wilkinson recognized the exceptionally mild reaction conditions and high selectivities attainable in such systems. However, Pruett and Smith of the Union Carbide Corporation reported first that the selectivity of the reaction to produce a high ratio of n- to i- aldehyde products is directly proportional to the excess triphenylphosphine ligand (4). In contrast, they found that the... 

However, such chelate complexes have a cis-configuration and as such are not expected to produce a high ratio of n/i aldehyde products when used as hydroformylation catalysts. 

For cis-chelate complexes of rhodium and bisphosphines as catalysts, indeed relatively low ratios of n/i aldehyde products were reported (12, 13). Using a 1 1 mixture of H CO at atmospheric pressure, Sanger reported n/i ratios ranging from 3 to 4 for propylene hydroformylation (12). However, his catalyst systems were produced by adding less than 2 mol of bisphosphine per mole tris(triphenyl-phosphine)rhodium carbonyl hydride. When an excess of the chelating bisphosphines was used by Pittman and Hirao (13), low n/i ratios close to 1 were produced from 1-pentene using a mixture of H2/CO at 100-800 psi between 60° and 120°C. 

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