1. A process for preparing a benzyl-protected flavan-3-one of (+)-catechin comprises the steps of:
(a) protecting the 5, 7, 3\u2032, and 4\u2032 phenolic hydroxyl groups of (+)-catechin with benzyl groups; and
(b) oxidizing the benzyl-protected (+)-catechin of step (a) with Dess-Martin periodinane to form (2R)-5, 7, 3\u2032, 4\u2032tetrakis(benzyloxy) flavan-3-one.
2. An alcohol inversion process for converting 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl (\u2212)-catechintetra-O-benzyl-(+)-catechin to 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl (\u2212)-epicatechintetra-O-benzyl-(\u2212)-epicatechin comprises the steps of:
(a) oxidizing 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-(\u2212)-catechintetra-O-benzyl-(+)-catechin with Dess-Martin periodinane to form (2R)-5, 7, 3\u2032, 4\u2032-tetrakis-(benzyloxy) flavan-3-one; and
(b) reducing the protected flavan-3-one of step (b) with lithium tri-sec-butylborohydride in the presence of a Lewis acid to form the 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-(\u2212)-epicatechin.
3. A process for preparing (2R)-5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-(\u2212)-epicatechin comprises the steps of:
(a) protecting the 5, 7, 3\u2032, and 4\u2032 phenolic hydroxyl groups of (+)-catechin with benzyl groups;
(b) oxidizing the alcoholic hydroxyl group at the 3-position of the protected (+)-catechin of step (a) with Dess-Martin periodinane to form (2R)-5, 7, 3\u2032, 4\u2032-tetrakis (benzyloxy) flavan-3-one; and
(c) reducing the protected flavan-3-one of step (b) with lithium tri-see-butylborohydride in the presence of a Lewis acid to form the (2R)-5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-(\u2212)-epicatechin.
4. The process of claim 1 or 3, wherein the protecting step is carried out with benzyl bromide in the presence of sodium hydride.
5. The process of claim 4, wherein the (+)-catechin is dissolved in anhydrous dimethylformamide.
6. The process of claim 5, wherein the benzyl bromide is added dropwise at room temperature to a stirred suspension of the (+)-catechin and sodium hydride in anhydrous dimethylformamide.
7. The process of claim 1, 2, or 3, wherein the oxidizing step is carried out in moist methylene chloride.
8. The process of claim 1, 2, or 3, further comprising the step of purifying the (2R)-5, 7, 3\u2032, 4\u2032-tetrakis (benzyloxy) flavan3-one by recrystallization from a chloroformether mixture.
9. The process of claim 2 or 3, wherein the reducing step is carried out with lithium-tri-sec-butylborohydride and a Lewis acid in tetrahydrofuran.
10. The process of claim 2 or 3, wherein the Lewis acid is anhydrous lithium bromide.
11. The process of claim 2 or 3, wherein the reaction mixture from the reducing step is treated with aqueous sodium hydroxide and then with aqueous hydrogen peroxide.
12. The process of claim 11, further comprising the step of adding ethanol to the reaction mixture.
13. The process of claim 12, further comprising the steps of dissolving the 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-epicatechintetra-O-benzyl-(\u2212)-epicatechin in chloroform, separating an aqueous phase and a chloroform phase, extracting the aqueous phase with chloroform, combining the chloroform phases, and dying the combined chloroform phase to recover crude 5, 7, 3\u2032, 4\u2032-tetra-O-benzyl-(\u2212)-epicatechin.
14. The process of claim 13, further comprising the step of dissolving the crude 5,7,3\u2032,4\u2032-tetra-O-benzyl-(\u2212)-epicatechin in a mixture of boiling ethyl acetate and ethanol and allowing the 5,7,3\u2032,4\u2032-tetra-O-benzyl-(\u2212)-epicatechin to crystallize.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Apparatus for electrically isolating a vehicle fuel receptacle from a vehicle body and tank system comprising: an exterior vehicle tank inlet receptacle engageable with a refueling nozzle; the receptacle comprising a vehicle body interior flange and a mating vehicle body exterior flange having an extending section interiorly concentric with the interior flange, the flanges disposed to sandwich the section of the vehicle body upon which the receptacle is mounted, the interior flange and the exterior flange affixed to the vehicle body by a plurality of fasteners insulated from the vehicle body wherein an insulating gasket essentially coextensive with the surface of the exterior receptacle flange is disposed between the exterior flange and the vehicle body.
2. Apparatus of claim 1 wherein the interior flange and the exterior flange and the insulating gasket are concentric and concentrically extending sections of the flanges and gasket are secured with respect to the vehicle body by electrically non-conducting fasteners.
3. Apparatus of claim 2 wherein the fasteners are electrically conductive and are insulated from the flanges and vehicle body by insulating grommets.
4. Apparatus of claim 1 including an o-ring disposed within the interior extending section of the interior flange adjacent the end of the concentric section of the exterior flange that extends within the interior flange.
5. Apparatus of claim 1 including an insulating sleeve disposed around the outer surface of the extending interior section of the exterior flange.
6. Apparatus of claim 4 wherein the sleeve extends beyond the end of the extending interior section of the exterior flange and folds inwardly at the end thereof.
7. Apparatus of claim 4 or claim 5 including a recessed o-ring disposed within the interior extending section of the interior flange between the sleeve and the extending section of the interior flange.
8. Apparatus of claim 4 or claim 5 including a pair of recessed o-rings, a first o-ring disposed within the interior extending section of the interior flange and a second o-ring disposed within the interior extending section of the exterior flange, the o-rings disposed within the flange sections such that the o-rings sandwich the sleeve.
9. Apparatus of claim 7 wherein one o-ring is formed from a metal and the second o-ring is formed from an electrically insulating material.
10. Apparatus of claim 4 or claim 5 wherein the sleeve comprises a cylindrical metallic collar having interior and outer surfaces covered with an electrical insulator.
11. Apparatus of claim 9 wherein the electrical insulator comprises a surface coating of a polymeric material.
12. Apparatus of claim 7 in which the o-rings are longitudinally offset from one another.
13. Apparatus of claim 7 in which the o-rings are longitudinally aligned with one another.
14. Apparatus for electrically isolating a vehicle fuel receptacle from the vehicle comprising a vehicle fuel tank inlet receptacle engageable with a refueling nozzle; the receptacle comprising (a) a vehicle body flange having an exterior flange section disposed with respect to the vehicle body and an interior section extending from the exterior section toward the vehicle body interior; (b) an insulating gasket disposed between the exterior flange and the vehicle body in a sandwich relationship; (c) a terminal plate affixed to the interior extending end section of the vehicle body flange; and (d) an electrically insulating plate gasket disposed between the end section of the vehicle body flange and the terminal plate; (e) the flange, gaskets and plate being collinearly concentrically aligned.
15. Apparatus of claim 13 wherein the insulating gasket disposed between the exterior flange and the vehicle body is flange shaped and has a central collar section extending over the inward extending section of the exterior flange between the outer circumference of the extending section and the vehicle body.
16. Apparatus of claim 14 wherein the circumferentially extending section of the exterior flange is concentrically aligned with the gasket and the flange and gasket are secured to the vehicle body by electrically insulating fasteners.
17. Apparatus of claim 14 wherein the circumferentially extending section of the exterior flange is concentrically aligned with the gasket and the flange and gasket are secured to the vehicle body by electrically conductive fasteners that are electrically insulated from the vehicle body by insulating grommets.
18. Apparatus of claim 13 wherein the plate at the exterior flange is concentrically aligned with the plate gasket and the flange and the flange and plate gasket are secured to the vehicle body by electrically insulating fasteners.
19. Apparatus of claim 13 wherein the circumferentially extending section of the exterior flange is concentrically aligned with the plate gasket and the flange and plate gasket are secured to the vehicle body by metal fasteners that are electrically insulated from the vehicle body by insulating grommets.
20. Apparatus of claim 13 wherein the plate gasket comprises a metal washer coated with an electrically insulating material.
21. Apparatus of claim 13 including a pair of concentric o-rings, a first o-ring recessed within the interior facing end of the extending section of the exterior flange, the second o-ring recessed within exterior facing end of the plate, wherein the plate gasket is disposed between the o-rings.
22. Apparatus of claim 15 or claim 16 including a reverse flange at the interior facing end of the extending section of the exterior flange having means for receiving therein a fastener for securing the plate.