B757-200 LOST CABIN PRESSURIZATION. EMER DESCENT WAS INITIATED AND FLT DIVERTED.

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NORMAL DEP AND WE WERE CLRED ON COURSE. ATC CLRED US TO FL340. ACFT RESTR TO FL350 MAX BECAUSE L BLEED OFF AND L PACK OFF AS PER MEL. ABOUT 10 MINS AFTER LEVELOFF; MASTER WARNING ACTIVATED ALONG WITH CABIN ALT ALERT ON FORWARD PANEL. CABIN ALT APPROX 11000 FT. WE IMMEDIATELY DONNED OXYGEN MASKS AND DID A COM CHK. WE ASKED FOR LOWER FROM ATC AND STARTED A RAPID DSCNT TO 10000 FT. WE ASKED FOR AND WERE CLRED DIRECT TO ZZZ WHILE COMPLETING THE RED BOX PROC FOR RAPID DEPRESSURIZATION AND EMER DSCNT. DURING DSCNT; PASSING 17000 FT; WE STARTED THE APU AND PUT THE L PACK ON LINE (PER MEL). AT THIS POINT; FLT ATTENDANTS RPTED SOME SMOKE IN THE CABIN. WE ONLY SMELLED A LIGHT PUNGENT ODOR IN THE COCKPIT BUT WENT AHEAD AND COMPLETED THE RED BOX FOR CABIN SMOKE. BEFORE WE COMPLETED THE CHKLIST THEY CALLED TO SAY THE SMOKE HAD CLRED. CLRNC WAS RECEIVED AT THIS POINT TO INTERCEPT FINAL FOR RWY 11 AND CLRED VISUAL. WE LANDED APPROX 20 MINS LATER AND STOPPED ON THE RWY SO CFR COULD EXAMINE THE EXTERIOR TO MAKE SURE THERE WAS NO SMOKE COMING FROM THE ACFT. THEY DETERMINED THAT THERE WAS NO SMOKE OR FIRE; SO WE PARKED THE ACFT AND DEPLANED THE PAX WITHOUT FURTHER INCIDENT.