There is a tiny two-block alleyway in West Los Angeles that runs on a diagonal from South Barrington Avenue east to Pico Boulevard. The backs of small industrial buildings border one side. On the other, a chain link fence shields a packinghouse or shipping service. To look at it, you would never call it the street of dreams or the isle of atmospheric romantic intrigue. You certainly would never envision it as the pulsating focus of a once-young, vibrant new generation of American Jews animated by the lightning victory of Israeli soldiers during the Six-Day War.