A practical route to partially protected pyrrolidines as precursors for the stereoselective synthesis of alexines.

Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by sodium azide in DMF, respectively. Compound 6b was also prepared from 4b in one step by the Mitsunobu methodology. Deacetonation of 6a and 6b gave the partially protected free azidouloses 8a and 8b, respectively, that were protected as their 1-O-TBDPS derivatives 9a and 9b. Hydrogenation of 9b over Raney nickel gave stereoselectively (2R,3R,4R,5S)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (12) which was identified by transformation into the well known (2R,3R,4R,5S)-3,4-dihydroxy-2,5-bis(hydroxymethyl)pyrrolidine (1, DGDP).

Occupational and environmental medicine in Colombia.

Colombia is a country rich in natural resources, with a steadily developing economy. Occupational and environmental medicine (OEM) education and practice have developed relatively recently in Colombia, mainly in response to a series of long overdue (and still partially implemented) reforms to the health care, social benefits, and education systems. Expansion in general and occupational health coverage of the Colombian population and development of OEM education and training were to be achieved through a clear stimulus to private sector initiatives. Despite some measurable overall progress, the goals remain elusive. This article discusses several aspects and the perspectives for further development of the specialty in this country, in the context of the socioeconomic factors involved in that process.

Microbiologic contamination of peripheral blood progenitor cells collected for hematopoietic cell transplantation.

BACKGROUND: Peripheral blood progenitor cells (PBPCs) rather than bone marrow are used increasingly to provide hematologic reconstitution when transfused after marrow-ablative chemotherapy. PBPCs often are collected via central venous catheters that have remained in place for long periods of time and that may become infected. STUDY DESIGN AND METHODS: The investigators reviewed their 5-year experience in collecting PBPCs for the prevalence of bacterial contamination. Except for cotrimoxazole therapy given to prevent Pneumocystis cariini pneumonia, patients were not given antibiotic prophylaxis. RESULTS: Each patient underwent a median of 7 (range, 2-21) PBPC collections; 0.2 percent (3/1040 collections) were culture positive for bacteria (two collections contained coagulase-negative staphylococci and one contained Serratia marcescens). All culture-positive collections were discarded; no PBPCs were culture positive at the time of thawing and transfusion. CONCLUSION: This contamination rate is below that previously reported for bone marrow harvests and platelet concentrate collections. Obtaining PBPCs through large-bore central venous catheters has not added to the risk of infection in transplant patients. A program of screening in vitro cultures and strict adherence to sterility techniques can result in very low microbiologic contamination and thus obviates the need for prophylactic antimicrobials in the PBPCs and in the patient.

Enantiospecific synthesis fromD-fructose of (2S,5R)- and (2R,5R)-2-methyl-1,6-dioxaspiro[4.5]decane [the odor bouquet minor components ofParavespula vulgaris (L.)].

The synthesis of (2S,5R)-(1) and (2R,5R)-2-methyl-1,6-dioxaspiro [4.5]decane (2) from (2RS,5R,8R,9R,10S)-8,9,10-trihydroxy-2-methyl-1, 6-dioxaspiro[4.5]decane (8), obtained in five steps fromD-fructose using Wittig's methodology, reduction, and spiroketalation, has been accomplished by a Corey dideoxygenation at C-8,9, followed by a Barton deoxygenation at C-10, of the appropriately protected derivatives.

Enantiospecific synthesis of (3S,6R)-3-hydroxy-1,7-dioxaspiro[5.5]undecane and its (4R)-4-hydroxy isomer [minor components of olive fruit fly (Dacus oleae) sex pheromone].

The synthesis of (3S,6R)-3-hydroxy-1,7-dioxaspiro[5.5]undecane (8) and its (4R)-4-hydroxy isomer (11) from (3R,4S,6R)-3,4-dihydroxy-1,7-dioxaspiro[5.5]undecane (1), obtained from D-fructose, has been accomplished by regioselective deoxygenation at C-4 and C-3, respectively, of the appropriately protected derivatives.

Enantiospecific synthesis of (R)-1,7-dioxaspiro [5.5]undecane [major component of olive fruit fly (Dacus Oleae) sex pheromone] from d-Fructose.

The synthesis of the title compound13 has been carried out through the preparation of its precursor, (3R,4R,5S,6R)-3,4,5-trihydroxy-1,7-dioxaspiro[5.5]undecane (6), obtained fromD-fructose using Wittig's methodology, reduction, and spiroketalation. Compound6 was transformed into13 by a Barton deoxygenation at C-5 followed by a Corey dideoxygenation at C-3,4 of the appropriately protected derivatives.