Papers by María Dolores Rodríguez Ruiz
Tetrahedron: Asymmetry, 2002
Aldol additions of metalated bis-lactim ethers derived from cyclo-[Gly-D-Val] 3A-E* to mismatched... more Aldol additions of metalated bis-lactim ethers derived from cyclo-[Gly-D-Val] 3A-E* to mismatched L-erythrose-derivatives 4a and 4b have been studied. Reactions of titanium(IV) and tin(II) azaenolates with the lactol derivative 4b allow direct and moderate (syn,syn)-or highly (anti,anti)-selective access to polyhydroxy amino acids that have been efficiently transformed into 1-deoxy-D-gulonojirimycin or 1-deoxy-D-allonojirimycin.
Tetrahedron: Asymmetry, 2002
Ab initio (RHF/6-31G*) and two-layer hybrid ab initio:semi-empirical (ONIOM) calculations were ca... more Ab initio (RHF/6-31G*) and two-layer hybrid ab initio:semi-empirical (ONIOM) calculations were carried out to investigate the syn,anti-selective aldol additions of lithiated Schö llkopf%s bis-lactim ether to 1,3-dioxolane-4-carboxaldehydes. Initial lithium-carbonyl coordination to form a disolvated complex with 4.6-8.4 kcal/mol exothermicity is followed by the rate-determining reorganization to the aldolate products through six-membered chair-like transition structures. The experimental stereoselectivities of the aldol additions have been adequately reproduced. According to the calculations, the most stable transition structures are characterized by a non-Anh conformation of the aldehyde moiety. In addition, the b-methyl substituent of the aldehyde, trans to the carbonyl group, is found to increase the energy barrier of the competitive pathways, thus reinforcing the syn,anti-stereoselection of the aldol process.
Tetrahedron Letters, 1996
... All rights reserved PII: S00404039(96)01 1732 00404039 96 15.00 + 0.00 Amino Acid Based Diast... more ... All rights reserved PII: S00404039(96)01 1732 00404039 96 15.00 + 0.00 Amino Acid Based Diastereoselective Synthesis of Eisaminose Maria Ruiz, Vicente Ojea and Jos M" Quintela* Depanamento de Qutmica Fundamental e ... See Rose, JE, Leeson, PD; Gani, DJ Chem. Soc. ...
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Papers by María Dolores Rodríguez Ruiz