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(-)-Menthone, an inexpensive chiral auxiliary, was used to prepare both enantiomers of alpha-amino acids, amino alcohols, or oxazolidinones. The sequence includes the S(N)2' displacement by a cuprate reagent and a Curtius rearrangement as key steps.

[reaction: see text] AlMe(3) dramatically increases the diastereoselectivity of addition of vinyllithiums to alpha-chiral aldehydes but decreases that of methyllithium. Our results are explained in terms of an addition of the free vinyllithium on the Me(3)Al-aldehyde complex.

Purpose: To study the outcome of corneal transplants performed with cryopreserved tissue., Methods: Maisonneuve-Rosemont Hospital medical records of all corneal transplantations performed with cryopreserved tissue by one surgeon (M.L.F.) between March 1978 and April 1991 were reviewed. The Kaufman--Capella cryopreservation technique was used. Corneas were cryopreserved for periods of 3 days to 16.8 years (mean, 4.6 years) before transplantation., Results: We report a mean follow-up of 54 months (range, 2.8--151.3 months). Survival analysis showed the probability of a clear graft to be 76% at 1 year and 73.2% at 2 years. At the time of the last visit, visual acuity was 20/40 or better in 61 eyes (49.2%). The mean postoperative pachometry was 0.58 mm (range, 0.50--0.75 mm). Specular microscopy performed in 57 eyes showed a mean endothelial cell count of 938 cells/mm(2) 55.1 months (range, 2.9--151.3 months) after surgery. For comparison purposes, the outcome of a subgroup of cryopreserved (n = 33) and noncryopreserved (n = 26) corneas transplanted by the same surgeon between April 1986 and April 1990 was studied., Conclusion: Despite an increase in the primary failure rate and higher initial endothelial cell loss, cryopreserved transplants are viable. Although we do not recommend cryopreservation of corneas for elective surgery, we consider that cryopreserved corneas can be very useful in emergency situations when tissue availability is a problem.